the basics of cancer copyrighted material · the basics of cancer ... a breast cancer can spread to...

. .

If the three worst words are, ‘You have cancer’, then the four worst are ‘Yourcancer is back’.

Katie Couric, American newscaster and journalist

1

The basics of cancer

Very little strikes more fear into peoples’hearts than being told they have cancer.Such a diagnosis can turn a person’s worldupside down and conjure up thoughts ofwhat lies ahead: pain, disfigurement, dis-ability, nausea, hair loss, or even death.Recent years, however, have seen extra-ordinary advances in basic cancer researchand in the development of more effect-ive methods for the detection, diagnosis,and treatment of cancer. Consequently,while the phrase “You have cancer,” maybe life-altering, it is not necessarily the devastating, life-threatening diagnosis ofgenerations past.

CANCER IS A COMPLEX ENTITY

In the most basic sense, cancer is theabnormal, uncontrolled growth of previ-ously normal cells. The transformation ofa cell results from alterations to its DNAthat accumulate over time. The change inthe genetic information causes a cell to nolonger carry out its functions properly. A

CHAPTER CONTENTS

• Cancer is a complex entity• Cancer through the ages• Modern day cancer research and

treatment• Prevalence and mortality varies with

each cancer• Risk factors have been identified• Will cancer be conquered within our

lifetime?• Expand your knowledge• Additional readings

Cancer: Basic Science and Clinical Aspects, 1st edition.By C. A. Almeida and S. A. Barry. Published 2010by Blackwell Publishing, ISBN 978-1-4051-5606-6.

9781405156066_4_001.qxd 9/29/09 11:28

COPYRIG

HTED M

ATERIAL

primary characteristic of cancer cells is their ability to rapidly divide, andthe resulting accumulation of cancer cells is termed a tumor. As the tumorgrows and if it does not invade the surrounding tissues, it is referred toas being benign (Figure 1.1a). If, however, the tumor has spread to nearbyor distant tissues then it is classified as malignant (Figure 1.1b).

Metastasis is the breaking free of cancercells from the original primary tumorand their migration to either local or dis-tant locations in the body where theywill divide and form secondary tumors.

There are many types of cancer

Cancer is not a single disease; there are over 100 identified types, all withdifferent causes and symptoms. To distinguish one form from another the cancers are named according to the part of the body in which theyoriginate. Some tumors are identified to reflect the type of tissues theyarise from, with the suffix -oma, meaning tumor, added on. For example,myelos- is a Greek term for marrow. Thus, myeloma is a tumor of the bone

2 CHAPTER 1 THE BASICS OF CANCER

. . . .

(a) Benign tumors are generally self-contained and localized and have a well-defined perimeter

They are dangerous whenthey compress surroundingtissues. A benign tumornear a blood vessel couldrestrict the flow of blood;in the abdomen it couldimpair digestion; in thebrain it could causeparalysis They grow slowly,

expanding outward from a central mass

(b) Malignant tumors arenot self-contained, andusually do not compresssurrounding tissues. Theirgrowth is an irregularinvasion of adjacent cells

They are not localized; ina process called metastasisthey shed cells that travelthrough the bloodstreamand infect tissues at otherlocations. They can evenestablish malignant growthin a different type of tissue:a breast cancer can spreadto bone tissue, for example

Although they maygrow slowly, they arealso capable of veryrapid growth

Figure 1.1 Benign vs. malignant cancers. (a) A benign tumor is a mass of cells that remains within the tissue in which it originally developed. (b) The invasion of cancer cells into surrounding tissues is the hallmark of a malignant tumor. Malignant cells may break free from the tumor and travel to other locations in the body through the process of metastasis. Source: http://health.stateuniversity.com/pages/1580/Tumor-Removal.html

?Do benign or malignant cellsform metastatic tumors?

9781405156066_4_001.qxd 9/29/09 11:28

marrow, whereas hepatoma is liver cancer (hepato- = liver), and melanomais a cancer of melanocytes, cells found primarily in the skin that producethe pigment melanin. (Table 1.1)

There are four predominant types of cancer

The four major types of cancer are carcinomas, sarcomas, leukemias, andlymphomas. Approximately 90% of human cancers are carcinomas, whicharise in the skin or epithelium (outer lining of cells) of the internal organs,glands, and body cavities. Tissues that commonly give rise to carcinomasare breast, colorectal, lung, prostate, and skin. Sarcomas are less commonthan carcinomas and involve the transformation of cells in connective tissue such as cartilage, bone, muscle, or fat. There are a variety of sarcomasubtypes and they can develop in any partof the body, but most often arise in thearms or legs. Liposarcoma is a malignanttumor of fat tissue (lipo- = fat) whereasa sarcoma that originates in the bone iscalled osteosarcoma (osteo- = bone).

Certain forms of cancer do not form solid tumors. For example,leukemias are cancers of the bone marrow, which leads to the over-production and early release of immature leukocytes (white blood cells).Lymphomas are cancers of the lymphatic system. This system, which is acomponent of the body’s immune defense, consisting of lymph, lymph ves-sels, and lymph nodes, serves as a filtering system for the blood and tissues.

Each cancer is unique

While there are certain commonalities shared by cancers of a particulartype, each may be unique to a single individual. This is because of differentcellular mutations that are possible, and can depend on whether the dis-ease is detected at an early or advanced stage. As a result, two womendiagnosed with breast cancer may or may not receive the same treatment.The impact of the disease on the individual, as well as the final outcomeof the disease, is unique in every case. Still, several types of cancers canhave a similar set of symptoms, which may be shared with several otherconditions, making screening, detection, and diagnosis a complex problem.

A tumor can impact the function of the tissue in which it resides orthose in the surrounding areas. Tumors provide no useful function them-selves and may be considered “parasites,” with every step of their advancebeing at the expense of healthy tissue (Figure 1.2). While most types ofcancers form tumors, many do not form discrete masses. As previouslystated, leukemia is a cancer of the blood that does not produce a tumor,but rather rapidly produces abnormal blood cells in the bone marrow atthe expense of normal blood cells.

CHAPTER 1 THE BASICS OF CANCER 3

. . . .

?What is the difference betweenthe terms hepatoma andhepatocarcinoma?

9781405156066_4_001.qxd 9/29/09 11:28


. . . .

Tab

le 1

.1T

um

or

term

ino

logy

Pre

fix

Cel

l ty

pe

Ben

ign

tu

mo

rM

alig

nan

t tu

mo

rT

issu

e af

fect

ed

Tu

mor

s of

epi

thel

ial

cell

s:A

den

o-

Gla

nd

Aden

om

aA

den

oca

rcin

om

aB

reas

t, c

olo

n/r

ectu

m,

lun

g, o

vary

,pan

crea

s, p

rost

ate

Bas

al c

ell

Bas

al c

ell

Bas

al c

ell

aden

om

aB

asal

cel

l ca

rcin

om

aSkin

Squ

amou

s ce

llSqu

amou

s ce

llK

erat

oac

anth

om

aSqu

amou

s ce

ll c

arci

nom

aE

soph

agu

s, l

aryn

x,

lun

g, o

ral

cavi

ty,

ph

aryn

x,

skin

, ce

rvix

Mel

ano-

Pig

men

ted c

ell

Mole

Mel

anom

aSkin

Tu

mor

s of

su

ppor

tin

g ti

ssu

e or

igin

:H

eman

gio-

Blo

od v

esse

lsH

eman

giom

aH

eman

giosa

rcom

aB

lood v

esse

ls

Lip

o-

Fat

Lip

om

aLip

osa

rcom

aFat

cel

ls

Men

ingi

o-

Men

inge

sM

enin

giom

aM

enin

giosa

rcom

aB

rain

Myo

-M

usc

leM

yom

aM

yosa

rcom

aM

usc

le

Ost

eo-

Bon

eO

steo

ma

Ost

eosa

rcom

aB

on

eE

win

g’s

sarc

om

a

Can

cers

of

bloo

d an

d ly

mph

atic

ori

gin

:Lym

ph

o-

Lym

ph

ocy

teLym

ph

om

aLym

ph

ocy

tes

Lym

ph

ocy

tic

leu

kem

ia

Mye

lo-

Bon

e m

arro

wM

yelo

ma,

Gra

nu

locy

tes

Mye

loge

nou

s le

ukem

ia

9781405156066_4_001.qxd 9/29/09 11:28

The development of tumors

All tumors begin with mutations (changes) that accumulate in the DNA(genetic information) of a single cell causing it and its offspring to func-tion abnormally. DNA alterations can be sporadic or inherited. Sporadicmutations occur spontaneously during the lifespan of a cell for a num-ber of reasons: a consequence of a mistake made when a cell copies itsDNA prior to dividing, the incorrect repair of a damaged DNA molecule,or chemical modification of the DNA, each of which interferes with expres-sion of the genetic information. Inherited mutations are present in theDNA contributed by the sperm and/or egg at the moment of conception.To date, 90–95% of diagnosed cancers appear to be sporadic in natureand thus have no heredity basis. Whether the mutations that result in acancer are sporadic or inherited, certain genes are altered that negativelyaffect the function of the cells.

Genetic influence on tumors

A link between a particular genetic mutation and one or more types ofcancers is made by analyzing and comparing the DNA of malignant tissue samples obtained from patients and members of families with a highincidence of a particular cancer and comparing it to the DNA from healthy


. . . .

(a) (b)

Figure 1.2 (a) Healthy lung and (b) cancerous lung. Reprinted withpermission © American Lung Association. For more information about the American Lung Association or to support the work it does, call 1-800-LUNG-USA (1-800-586-4872 or log on to www.lungusa.org)

9781405156066_4_001.qxd 9/29/09 11:28

. .

individuals. For example, a study could be conducted in which the DNAisolated from tumor cells obtained from liver cancer patients is analyzedand determined to possess certain versions of genes whereas different versions of those same genes are present in the DNA of liver cells of healthypersons. An association could then be drawn between the “bad” versionsof those genes and liver cancer.

This type of analysis has been crucial in identifying certain versions ofgenes associated with a predisposition for the development of particularforms of cancer. For example, studies have demonstrated that there is anelevated risk of breast or ovarian cancer associated with certain versionsof the BRCA1 and/or BRCA2 genes (Chapter 8). Another example is retinoblastoma, a rare tumor of the eye typically found in infants andyoung children, which is associated with alterations within the Rb gene(Chapter 4).

CANCER THROUGH THE AGES

Although not specifically identified as such, cancer has been known for manycenturies. In fact, there is evidence of tumors in the bones of five thousandyear old mummies from Egypt and Peru. The disease itself was not verycommon, nor explored or understood, because in ancient times fatal infec-tious diseases resulted in shorter lifespans. Given that the vast majorityof cancers are sporadic, there was less opportunity for the accumulationof the mutations necessary to transform normal cells into cancerous ones.

The word “cancer” was first introduced by Hippocrates (460–370 BC), theGreek physician and “father of medicine” (Figure 1.3). He coined the termcarcinoma, from the Greek word karcinos, meaning “crab,” when describingtumors. This is because tumors often have a central cell mass with exten-sions radiating outward that mimic the shape of the shellfish (Figure 1.4).

Hippocrates believed that the body contained four “humors” or bodyfluids, and that each fluid was associated with a specific personality ortemperament characteristic. “Blood” persons had a sanguine or optimisticpersonality with a passionate, joyous disposition. Someone with a dullor sluggish temperament would have “Phlegm.” Possessing “Yellow Bile”meant that one was quick to anger, while having “Black Bile” indicateda person was melancholic or depressed. In medieval times, it was believedthat disease was a result of an imbalance of any of the four humors andphysicians could restore health or harmony by purging, starving, vomiting,or bloodletting. In particular, an excess of black bile was thought to bethe primary cause of cancer. This theory was accepted and taught for over1300 years through the Middle Ages and championed by Claudius Galen(131–201 AD), a Greek physician and writer who described many diseasesusing this hypothesis (Figure 1.5). Both Hippocrates and Galen defineddisease as a natural process, a theory that remained for centuries.


. .

9781405156066_4_001.qxd 9/29/09 11:28


. .. .

Figure 1.3 Hippocrates is history’s most famous physician.

Figure 1.4 A cancer cell that has extensions extending out from the central body of the cell. Source: National Cancer Institute Visuals Online;http://visualsonline.cancer.gov/

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

Figure 1.5 Claudius Galen is considered by some to be the second mostimportant contributor to medicine, after Hippocrates, in ancient times.

Box 1.1

Bloodletting as a medical practice

Interestingly, bloodletting is a method used in modern medical practice. The FDAformally approved the use of leeches as medical devices in June 2004. The inverte-brate bloodsuckers are most often used following reconstructive surgery for thereattachment of fingers and toes to remove the excess blood that accumulatesfrom severely damaged blood vessels. Since pooled blood often inhibits the heal-ing of wounded tissues, the leeches’ ability to extract it is beneficial and efficient.Hirudin is an effective anti-blood clotting agent present in the saliva of the leechthat keeps the blood flowing, giving time for the vessels and tissues to heal. Althoughit seems as if leech therapy would be painful, it is not thanks to a mild anestheticthe leeches produce.

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

The use of autopsies is very significant to medical discoveries

Unfortunately, during the Middle Ages the dissection of cadavers was largelyprohibited for religious reasons, or yielded little data when conducted at all, due to its primitive nature. The failure to recognize the benefits of studying cadavers, or the understandable ignorance of the times,arguably delayed the progress of medical science. As a result, one of medi-cine’s most informative research tools, dissection of cadavers, was largelyignored.

The English physician William Harvey (1578–1657) is credited with con-ducting the first examples of postmortem (after death) analysis (Figure 1.6).Although rare and certainly unscientific by modern standards, his “publicdissections” are now known as autopsies. Giovanni Morgagni (1682–1771),an Italian physician, is considered the founder of pathological anatomy(Figure 1.7). In 1761, at the age of 79, he published a book describingnearly 700 autopsies that he had performed associating a patient’s causeof death to the pathological findings made postmortem. His work was afar cry from the theory of “humors” that had previously existed and laidthe foundation for the serious study of cancer as a cause of morbidity(disease) and mortality (death).

Figure 1.6 William Harvey was the first, as a result of performing manyautopsies, to demonstrate that the heart pumped the blood around the bodythrough arteries and veins.

9781405156066_4_001.qxd 9/29/09 11:29

. .

Early discovery of carcinogens

Also published in 1761 was a paper by John Hill, an English physician.In it he made the first causal link between substances in the environmentand cancer when he described a relationship between tobacco snuff andnasal cancer. This brought about the awareness of carcinogens (chemicalagents that have been demonstrated to cause cancer). In 1775, the Englishsurgeon Sir Percivall Pott observed and noted a high rate of scrotal canceramong chimney sweepers. He postulated that it was caused by long-termexposure to the chemicals in the soot-soaked ropes worn as harnesses.His research led to studies that associated particular occupations with anincreased risk of developing specific forms of cancer – the forerunner tothe field of public health and cancer.

The use of microscopes demonstrated changes at a cellular level

The development of improved microscopes in the late nineteenth centuryallowed for more thorough examinations of cells and their activities thanwas previously possible. It was realized that cancer cells were different


. .

Figure 1.7 Giovanni Morgagni performed hundreds of autopsies in the 1700s,leading to verification of cancer as a cause of death.

9781405156066_4_001.qxd 9/29/09 11:29

in both appearance and behavior from normal cells within the same tis-sue or organ (Figure 1.8). Early twentieth century accomplishments in thedevelopment of cell culture (an in vitrotechnique for studying the activity ofcells in an organism under simulatedphysiological conditions1.1), new andimproved diagnostic techniques, the dis-covery of chemical carcinogens, and theuse of chemotherapy (powerful anti-cancer drugs) all had significant impactsupon the understanding and treatment ofcancer.

MODERN DAY CANCER RESEARCH AND TREATMENT

The radioactive element radium, isolated by Marie and Pierre Curie in1898, was found to be effective in the treatment of tumors in 1903. Whileboth healthy and cancerous cells are susceptible to the damage causedby X-rays, cancer cells are inherently less able to repair the damage andrecover. Once safe dosage levels were determined, radiation therapybecame a standard form of treatment for many cancers.

Public awareness of cancer

As the access to scientific knowledge increased, so too did the public’sfear and misconceptions. In the early 1900s the word “cancer” was rarelyspoken in public and it was omitted from obituaries, similar to how theuse of the word AIDS was avoided in the 1980s and 1990s. Surprisingly,the first widely published discussion of cancer was a 1913 Ladies HomeJournal magazine article that asked “What Can We Do About Cancer?”and listed the disease’s principal warning signs. With its large circulation,


. .. .

(a) (b)

Figure 1.8 (a) Note the abundance of the thin, sheet-like extensions from the cell bodies of the healthy cells. (b) Note the rounded appearance of the cancer cells. Source: National Cancer Institute Visuals Online;http://visualsonline.cancer.gov/

1.1 The term in vitro is Latin for “inglass” meaning that an experiment isbeing conducted in an artificial envir-onment, such as a glass test tube. Thecomplementary Latin term in vivomeans “in life,” implying that some-thing is occurring in a living organism.

9781405156066_4_001.qxd 9/29/09 11:29

. .

the magazine brought the word “cancer” to the forefront of public aware-ness and discussion. That same year in New York City, a group of tenphysicians and five laypeople established the American Society for theControl of Cancer (ASCC). The group raised $10,000 that year, and pub-lished a pamphlet titled The Facts About Cancer. In 1945 the ASCC changedits name and to this day is known as the American Cancer Society (ACS).The following year, volunteer Mary Lasker and her colleagues raised over$4 million, an extraordinary amount at that time and even today, for theSociety. Of that sum, $1 million was allocated to establish the Society’scancer research program. In 1947 the ACS initiated its public educationcampaign concentrating on “The seven signs and symptoms of cancer,”utilizing the word “Caution” as a way to remember the first letter of eachsymptom:• Change in bowel or bladder habits.• A sore that does not heal.• Unusual bleeding or discharge.• Thickening or a lump in the breast or other parts of the body.• Indigestion that is chronic or difficulty in swallowing.• Obvious changes in a wart or mole.• Nagging cough or hoarseness.Although currently outdated due to its lack of specificity and discontinuedin the 1980s, the campaign served to provide enormous awareness amongpeople who, for the first time, were encouraged to be aware of and onthe lookout for possible signs and symptoms of cancer.

Unexpected discoveries result in some cures

The first clinical use of a dramatic new form of cancer treatment –chemotherapy – occurred in the 1940s. Soldiers in World War I whowere exposed to the chemical warfare agent known as mustard gaswould develop painful blisters on their skin and eyes. If the gas was inhaled,their ability to breathe was severely compromised because the gas woulddestroy the mucous linings of their lungs. It was noted that those who

survived an attack developed low whiteblood cell counts. This led researchers toquestion whether mustard gas or a derivat-ive of it could be used to treat certain can-cers that affect white blood cells.

Shortly after World War II, a clinicalstudy determined that the injection (ratherthan inhalation) of the principal compon-ent of mustard gas caused the temporaryremission of lymphoma, a type of whiteblood cell cancer.1.2 As is commonly donewhen a molecule demonstrates potential


. .

1.2 The use of chemicals as weaponswas considered so horrific and inhu-mane that it was outlawed by an inter-national chemical weapons conventiontreaty in 1997. What is significant isthat the evil use of chemical warfareagainst people gave rise to the bene-ficial practice of chemotherapy in thewar against cancer.

9781405156066_4_001.qxd 9/29/09 11:29

clinical effectiveness, a large number of chemical variants were synthes-ized in an attempt to lessen the highly reactive nature of the original mustard gas compound while retaining, and eventually improving upon,its desired function.

The synthesis and testing of literally hundreds of molecules in animaland human trials have led to several of them becoming conventional cancer treatment regimens. Serendipitous findings similar to those asso-ciated with mustard gas tend to occur often in scientific discoveries and areexamples of some good coming from an unfortunate event.

Another milestone came in 1947 when Dr Sidney Farber of the HarvardMedical School treated children with acute leukemia, another form ofwhite blood cell cancer, with the drug aminopterin. The drug blocked thesynthesis of nucleotides, the building blocks of DNA. This effectively inhib-ited the division of the cancer cells because they were unable to replicatetheir DNA and the children entered into a cancer-free state of remission.Even though the remission period was only temporary, Dr Farber is cred-ited with the first successful use of chemotherapy.

Government funding was/is necessary

The National Cancer Institute Act was passed by the US Congress in 1937,creating the National Cancer Institute (NCI), with the goal of conducting


. .. .

Box 1.2

The Legacy of Henrietta Lacks

Henrietta Lacks died of cervical cancer in 1951 at the age of 31 at Johns HopkinsUniversity Hospital in Baltimore, Maryland. She might have long been forgottenby all except her family and friends. Instead, she lives on in the form of highlymalignant cells taken from the quarter-sized tumor that was removed from hercervix and that eventually invaded almost every organ of her body. Laboratoriesand research centers worldwide have been using these cells for many years. Giventhe code name HeLa, for the first two letters of her first and last names, these werethe first human cells known to thrive and multiply outside of the body. Still aliveand rapidly dividing to this day, HeLa cells have been used in the developmentof the polio vaccine, the search for causes of cancer and a cure for leukemia, thestudy of the growth of viruses, the mechanisms that control the expression of ourgenetic information, and the effects of drugs and radiation on cellular functions.Henrietta’s cells grow aggressively, producing an entirely new generation of cellsevery 24 hours. Unfortunately, at the time of her death and for years after, therewas no system of “informed consent” in medical research, so it took many yearsfor her family to discover the impact that she has had on science.

9781405156066_4_001.qxd 9/29/09 11:29

. .

and promoting cancer research. In 1971, President Richard M. Nixon signedthe National Cancer Act, legislation that provided federal funds for cancerresearch to fight the disease. This Act infused money and authority intothe NCI in order to more effectively carry out the national effort to under-stand and fight cancer. Thus the phrase “War on Cancer” was born. Aftermore than three decades the war remains ongoing, although great stridesoccur almost daily.

The field of oncology was born

One primary outcome of the research and focus on cancer has been theestablishment of the field of oncology, the medical subspecialty dealingwith the study and treatment of cancer. Previously, primarily family physicians treated people diagnosed with cancer and followed their carethroughout their illnesses. If a woman developed the disease she mighthave been treated by her gynecologist, a doctor who specializes in femalemedical issues and who did not have extensive cancer training. The bodyof knowledge physicians had to work with was limited, to say the least.Only 51 physicians attended the first meeting of the American Society ofClinical Oncology in 1964. Today the organization comprises more than25,000 members representing the principal oncology disciplines (med-ical, radiological, and surgical) as well as several subspecialties (geriatriconcology, pediatric oncology, gastrointestinal oncology, etc.). Governmentfunding and private research spurred by charitable giving and the tireless support of groups such as the American Cancer Society, St JudeChildren’s Research Hospital, and the Boston-based Jimmy Fund havehelped to raise cancer awareness. Unfortunately, as aging baby boomersbecome increasingly cancer-prone, medical schools cannot train enoughnew oncologists to satisfy the need for them. A 2007 report by theAssociation of American Medical Colleges estimates that by 2020, visitsto oncologists will increase by 48% while the projected number of oncologists is estimated to grow by only 14% over the same time period.It is hoped that medical schools will acknowledge this shortage and addressthe issue by taking an active role in recruiting a greater number of futureoncologists.

Currently, there are a wide variety of methods to diagnose and treatcancer. The ones used are dependent upon the type of cancer and its current stage and location within the body. Genetic links to the diseaseare being discovered at a rapid pace, enabling physicians to identify thosepatients who have a predisposition for the development of specific can-cers or will respond best to certain forms of treatment. It is hoped thatthis knowledge will encourage people to be more diligent in maintaininghealthy lifestyles and be more consistent in following recommendationsfor regular screening tests. Some treatments will be personalized basedon one’s genetic make-up and/or the specific genetic make-up of the tumor.


. .

9781405156066_4_001.qxd 9/29/09 11:29

While not all treatment options offer a “cure,” they enable a large num-ber of individuals to manage their disease and live fairly normal and fulllives.

The field of oncology is evolving and expanding, with research articlesbeing published almost weekly announcing links between certain versionsof genes and the risk for the development of a particular form of cancer,methods to either reduce certain cancer risks or detect the disease at anearlier stage, and treatment options that are more effective and increasethe chance for survival. Media reports are often based on a single study,and they are designed so as to have a “wow!” factor that will garner maximum public attention. As a result, one must be able to differentiatebetween a reputable study and a report that is not scientifically valid, andlearn to distinguish hype from reality. All too frequently, today’s establishedprotocols are challenged by tomorrow’s newest discoveries. For this reason,the integrity and accuracy of new research findings must withstand thetest of time and be constantly questioned and reviewed.

PREVALENCE AND MORTALITY VARIES WITH EACH CANCER

Unfortunately, most of us know or will know someone who has beendiagnosed with cancer. In 2008 an estimated 1.4 million Americans were newly diagnosed with cancer and approximately 565,000 died from the disease (Table 1.2). This ACS estimate does not include two forms of cancer. The first are those classified as carcinoma in situ (in theoriginal site), which are more commonly known as benign tumors. Theyare confined and have not invaded surrounding tissues. An exception tothis rule is carcinoma in situ of the urinary bladder which is reported because of its tendency to aggressively grow and progress to a malignantstate. The second form consists of nonmelanomas or basal and squamouscell skin cancers, which are the most common forms of skin cancer withover one million new cases per year. Because these skin cancers rarelyspread and are not life threatening, they are routinely removed and treatedon an outpatient basis in nonhospital settings and, as such, are rarelyreported to cancer registries.

Cancer rates are different for men and women

For men, the five most prevalent cancers, in decreasing order, are prostate,lung and bronchus, colorectal, urinary bladder, and skin melanoma. The most commonly diagnosed cancers in women are breast, lung andbronchus, colorectal, non-Hodgkin’s lymphoma, and skin melanoma. Lungand bronchus, colorectal, and pancreatic cancers are among the top fivemost fatal forms of the disease in both men and women. Ironically, thenumber one cancer killer for both men and women, lung and bronchus,


. .. .

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

Tab

le 1

.2E

stim

ated

new

can

cer

case

s an

d d

eath

s b

y s

ex,

US

A,

2008

*

Est

imat

ed n

ew c

ases

Est

imat

ed d

eath

s

Bo

th s

exes

Mal

eF

emal

eB

oth

sex

esM

ale

Fem

ale

All s

ites

1,4

37,1

80

745,1

80

692,0

00

565,6

50

294,1

20

271,5

30

Ora

l ca

vity

an

d p

har

ynx

35,3

10

25,3

10

10,0

00

7,5

90

5,2

10

2,3

80

Ton

gue

10,1

40

7,2

80

2,8

60

1,8

80

1,2

10

670

Mou

th10,8

20

6,5

90

4,2

30

1,8

40

1,1

20

720

Ph

aryn

x12,4

10

10,0

60

2,3

50

2,2

00

1,6

20

580

Oth

er o

ral

cavi

ty1,9

40

1,3

80

560

1,6

70

1,2

60

410

Dig

esti

ve s

yste

m271,2

90

148,5

60

122,7

30

135,1

30

74,8

50

60,2

80

Eso

ph

agu

s16,4

70

12,9

70

3,5

00

14,2

80

11,2

50

3,0

30

Sto

mac

h21,5

00

13,1

90

8,3

10

10,8

80

6,4

50

4,4

30

Sm

all

inte

stin

e6,1

10

3,2

00

2,9

10

1,1

10

580

530

Colo

n†

108,0

70

53,7

60

54,3

10

49,9

60

24,2

60

25,7

00

Rec

tum

40,7

40

23,4

90

17,2

50

An

us,

an

al c

anal

, an

d a

nore

ctu

m5,0

70

2,0

20

3,0

50

680

250

430

Liv

er a

nd i

ntr

ahep

atic

bile

du

ct21,3

70

15,1

90

6,1

80

18,4

10

12,5

70

5,8

40

Gal

lbla

dder

an

d o

ther

bilia

ry9,5

20

4,5

00

5,0

20

3,3

40

1,2

50

2,0

90

Pan

crea

s37,6

80

18,7

70

18,9

10

34,2

90

17,5

00

16,7

90

Oth

er d

iges

tive

org

ans

4,7

60

1,4

70

3,2

90

2,1

80

740

1,4

40

Res

pir

atory

sys

tem

232,2

70

127,8

80

104,3

90

166,2

80

94,2

10

72,0

70

Lar

ynx

12,2

50

9,6

80

2,5

70

3,6

70

2,9

10

760

Lu

ng

and b

ron

chu

s215,0

20

114,6

90

100,3

30

161,8

40

90,8

10

71,0

30

Oth

er r

espir

atory

org

ans

5,0

00

3,5

10

1,4

90

770

490

280

Bon

es a

nd j

oin

ts2,3

80

1,2

70

1,1

10

1,4

70

820

650

Soft

tis

sue

(in

clu

din

g h

eart

)10,3

90

5,7

20

4,6

70

3,6

80

1,8

80

1,8

00

Skin

(ex

clu

din

g ba

sal

and s

qu

amou

s)67,7

20

38,1

50

29,5

70

11,2

00

7,3

60

3,8

40

Mel

anom

a62,4

80

34,9

50

27,5

30

8,4

20

5,4

00

3,0

20

Oth

er n

on

-epit

hel

ial

skin

5,2

40

3,2

00

2,0

40

2,7

80

1,9

60

820

Bre

ast

184,4

50

1,9

90

182,4

60

40,9

30

450

40,4

80

Gen

ital

sys

tem

274,1

50

195,6

60

78,4

90

57,8

20

29,3

30

28,4

90

Ute

rin

e ce

rvix

11,0

70

11,0

70

3,8

70

3,8

70

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

Ute

rin

e co

rpu

s40,1

00

40,1

00

7,4

70

7,4

70

Ova

ry21,6

50

21,6

50

15,5

20

15,5

20

Vu

lva

3,4

60

3,4

60

870

870

Vag

ina

and o

ther

gen

ital

, fe

mal

e2,2

10

2,2

10

760

760

Pro

stat

e186,3

20

186,3

20

28,6

60

28,6

60

Tes

tis

8,0

90

8,0

90

380

380

Pen

is a

nd o

ther

gen

ital

, m

ale

1,2

50

1,2

50

290

290

Uri

nar

y sy

stem

125,4

90

85,8

70

39,6

20

27,8

10

18,4

30

9,3

80

Uri

nar

y bl

adder

68,8

10

51,2

30

17,5

80

14,1

00

9,9

50

4,1

50

Kid

ney

an

d r

enal

pel

vis

54,3

90

33,1

30

21,2

60

13,0

10

8,1

00

4,9

10

Ure

ter

and o

ther

uri

nar

y org

ans

2,2

90

1,5

10

780

700

380

320

Eye

an

d o

rbit

2,3

90

1,3

40

1,0

50

240

130

110

Bra

in a

nd o

ther

ner

vou

s sy

stem

21,8

10

11,7

80

10,0

30

13,0

70

7,4

20

5,6

50

Erd

ocr

ine

syst

em39,5

10

10,0

30

29,4

80

2,4

30

1,1

10

1,3

20

Th

yroid

37,3

40

8,9

30

28,4

10

1,5

90

680

910

Oth

er e

ndocr

ine

2,1

70

1,1

00

1,0

70

840

430

410

Lym

ph

om

a74,3

40

39,8

50

34,4

90

20,5

10

10,4

90

10,0

20

Hodgk

in l

ymph

om

a8,2

20

4,4

00

3,8

20

1,3

50

700

650

Non

-Hodgk

in l

ymph

om

a66,1

20

35,4

50

30,6

70

19,1

60

9,7

90

9,3

70

Mye

lom

a19,9

20

11,1

90

8,7

30

10,6

90

5,6

40

5,0

50

Leu

kem

ia44,2

70

25,1

80

19,0

90

21,7

10

12,4

60

9,2

50

Acu

te l

ymph

ocy

tic

leu

kem

ia5,4

30

3,2

20

2,2

10

1,4

60

800

660

Ch

ron

ic l

ymph

ocy

tic

leu

kem

ia15,1

10

8,7

50

6,3

60

4,3

90

2,6

00

1,7

90

Acu

te l

ymph

ocy

tic

leu

kem

ia13,2

90

7,2

00

6,0

90

8,8

20

5,1

00

3,7

20

Ch

ron

ic l

ymph

ocy

tic

leu

kem

ia4,8

30

2,8

00

2,0

30

450

200

250

Oth

er l

eukem

ia‡

5,6

10

3,2

10

2,4

00

6,5

90

3,7

60

2,8

30

Oth

er a

nd u

nsp

ecifi

ed p

rim

ary

site

s‡31,4

90

15,4

00

16,0

90

45,0

90

24,3

30

20,7

60

*Rou

nded

to t

he

nea

rest

10;

esti

mat

ed n

ew c

ases

excl

ude

basa

l an

d s

qu

amou

s ce

ll s

kin

can

cers

an

d i

n s

itu

carc

inom

as e

xce

pt

uri

nar

y bl

adder

.A

bou

t 67,7

70 f

emal

e ca

rcin

om

a in

sit

uof

the

brea

st a

nd 5

4,0

20 m

elan

om

a in

sit

uw

ill

be n

ewly

dia

gnose

d i

n 2

008.

†E

stim

ated

dea

ths

for

colo

n a

nd r

ectu

m c

ance

rs a

re c

om

bin

ed.

‡M

ore

dea

ths

than

cas

es s

ugg

ests

lac

k o

f sp

ecifi

city

in

rec

ord

ing

un

der

lyin

g ca

use

s of

dea

th o

n d

eath

cer

tifi

cate

s.

So

urc

e:E

stim

ated

new

cas

es a

re b

ased

on

1995–2

004 i

nci

den

ce r

ates

fro

m 4

1 s

tate

s an

d t

he

Dis

tric

t of

Colu

mbi

a as

rep

ort

ed b

y th

e N

ort

hA

mer

ican

Ass

oci

atio

n o

f C

entr

al C

ance

r R

egis

trie

s (N

AA

CC

R),

rep

rese

nti

ng

abou

t 85%

of

the

US p

opu

lati

on

. E

stim

ated

dea

ths

are

base

d o

n d

ata

from

US M

ort

alit

y D

ata,

1969 t

o 2

005,

Nat

ion

al C

ente

r fo

r H

ealt

h S

tati

stic

s, C

ente

rs f

or

Dis

ease

Con

trol

and P

reve

nti

on

, 2008.

Rep

rodu

ced w

ith

per

mis

sion

fro

m:

Am

eric

an C

ance

r Soci

ety.

Can

cer

Fac

ts a

nd

Fig

ure

s 20

08.

Atl

anta

: A

mer

ican

Can

cer

Soci

ety,

In

c.

9781405156066_4_001.qxd 9/29/09 11:29

. .

is the most preventable as well since smoking, the greatest risk factor forthis disease, is a lifestyle choice.

Americans are living longer; in 1900 men and women lived to an average age of 48 and 51 years, respectively, whereas today they can expectto live on average to 74.1 and 79.5 years. Over the same period therehave been tremendous advances in the prevention and treatment of infectious diseases, the disposal and recycling of sewage and solid waste,and the quality and safety of drinking water. As a result, there has been

a shift in the causes of death from infec-tious to chronic, noninfectious diseases.Today, cancer is second only to cardiovas-cular (heart) disease as a leading cause of death. According to the most recentinformation available from the Centersfor Disease Control and Prevention (CDC),more than 630,000 Americans died ofheart disease and approximately 560,000died from cancer in 2006; together, these noninfectious diseases account formore than 60% of all deaths.

The mortality rate of cancer has decreased

One of the most common means of determining the overall health of apopulation is to assess the number of deaths caused by disease. In a stun-ning 2006 announcement, the American Cancer Society reported that the actual number of Americans who died of cancer between 2002 and2003 dropped for the first time since 1930. This decline in cancer deathswas unexpected given the increases in US population and lifespans.Recent statistics have also shown decreases in mortality rates for specificcancers such as breast and colorectal. Without question, an increase in pub-

lic awareness, changes in diet and exercise,the number of people undergoing screen-ing and diagnostic tests, the availability and improved sensitivity and accuracy oftests that can detect the disease at earlier,more treatable stages, and the develop-ment of more effective and tolerabletreatment methods, are all responsiblefor this downturn.

RISK FACTORS HAVE BEEN IDENTIFIED

There are a wide variety of factors that determine a person’s risk of devel-oping a particular disease and cancer is no different. Nearly half of men


. .

?What is the difference betweeninfectious and noninfectiousdiseases?

Name two infectious diseasesand their causes.

Why is cancer more prevalent in older rather than youngerpeople?

?How does an increase in thenumber of people undergoingscreening and diagnostic tests forcancer play a role in decreasingthe number of people who diefrom the disease?

9781405156066_4_001.qxd 9/29/09 11:29

and two-thirds of women live their lives without developing or havingbeen diagnosed with cancer. Why are they cancer-free and not others?Conversely, what makes the others susceptible? There are no absoluteanswers to these questions but there are certain factors that have beenshown to contribute to a person’s risk of developing all, many, or onlycertain forms of cancer, and they include a person’s age, gender, weight,family history, sociological and economic status, lifetime exposure to sexhormones, lifestyle choices (whether or not a person eats a healthy diet,smokes, drinks alcohol, is physically active or inactive, etc.), and environ-mental and occupational exposures to carcinogens.

Aging and genetics contribute to the highest incidence of cancer cases

Disease does not discriminate – young, middle-aged, the elderly, men, andwomen are affected. As one grows older, however, the risk of developingvirtually all serious conditions and illnesses increases. This is a corollaryof life as susceptibility to all diseases increases as the body’s natural defensemechanisms begin to erode. There are a number of reasons why the rateof cancer incidence increases with age (Table 1.3). The longer a personlives, the more cell divisions take place within the body. Prior to when acell divides, the entire genome (all 46 chromosomes) is replicated so thateach daughter cell will obtain the same genetic information.1.3 The processof DNA synthesis is not perfect though and errors do get incorporatedinto the chromosomes. Problems arise when the alterations negatively affect genes that promote or inhibit theability of a cell to divide. Since mutationswill accumulate over time, the longer aperson lives, the greater the chance thatan individual will acquire a collection of mutations. If a set of key regulatorygenes is affected, it can cause a cell to godown the path of uncontrolled growth.

Other risk factors are also important

At the present time, an American man has a 50% chance of being diag-nosed with cancer in his lifetime, while an American woman has a 33%chance. This gender difference is likely the result of a number of factors,such as differences in occupations, lifestyle choices, and in exposure toand levels of certain hormones. For example, both men and women developbreast cancer but less than one man develops the disease for every 100women who are diagnosed. It has been determined that a large factor inthis gender discrepancy is the amount of estrogen a woman is exposedto during her lifetime.

Ethnicity and race are also risk factors for the development of certainforms of the disease (Table 1.4). Obstacles faced by minorities include being


. .. .

1.3 The use of the term “daughter cells”does not refer to the gender of thecells, but rather simply to indicate thatthey are the descendants of a parentalcell.

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

Tab

le 1

.3P

rob

abil

ity

of

dev

elo

pin

g in

vas

ive

can

cers

ov

er s

elec

ted

age

in

terv

als

by

sex

, U

S,

2002

–200

4*

Bir

th t

o 3

9 (%

)40

to

59

(%)

60 t

o 6

9 (%

)70

an

d O

lder

(%

)B

irth

to

Dea

th (

%)

All s

ites

†M

ale

1.4

2 (

1 i

n 7

0)

8.5

8 (

1 i

n 1

2)

16.2

5 (

1 i

n 6

)38.9

6 (

1 i

n 3

)44.9

4 (

1 i

n 2

)Fem

ale

2.0

4 (

1 i

n 4

9)

8.9

7 (

1 i

n 1

1)

10.3

6 (

1 i

n 1

0)

26.3

1 (

1 i

n 4

)37.5

2 (

1 i

n 3

)

Uri

nar

y M

ale

0.0

2 (

1 i

n 4

,477)

0.4

1 (

1 i

n 2

44)

0.9

6 (

1 i

n 1

04)

3.5

0 (

1 i

n 2

9)

3.7

0 (

1 i

n 2

7)

blad

der

‡Fem

ale

0.0

1 (

1 i

n 9

,462)

0.1

3 (

1 i

n 7

90)

0.2

6 (

1 i

n 3

84)

0.9

9 (

1 i

n 1

01)

1.1

7 (

1 i

n 8

5)

Bre

ast

Fem

ale

0.4

8 (

1 i

n 2

10)

3.8

6 (

1 i

n 2

6)

3.5

1 (

1 i

n 2

8)

6.9

5 (

1 i

n 1

5)

12.2

8 (

1 i

n 8

)

Colo

n a

nd

Mal

e0.0

8 (

1 i

n 1

,329)

0.9

2 (

1 i

n 1

09)

1.6

0 (

1 i

n 6

3)

4.7

8 (

1 i

n 2

1)

5.6

5 (

1 i

n 1

8)

rect

um

Fem

ale

0.0

7 (

1 i

n 1

,394)

0.7

2 (

1 i

n 1

38)

1.1

2 (

1 i

n 8

9)

4.3

0 (

1 i

n 2

3)

5.2

3 (

1 i

n 1

9)

Leu

kem

iaM

ale

0.1

6 (

1 i

n 6

24)

0.2

1 (

1 i

n 4

68)

0.3

5 (

1 i

n 2

88)

1.1

8 (

1 i

n 8

5)

1.5

0 (

1 i

n 6

7)

Fem

ale

0.1

2 (

1 i

n 8

37)

0.1

4 (

1 i

n 7

05)

0.2

0 (

1 i

n 4

96)

0.7

6 (

1 i

n 1

31)

1.0

6 (

1 i

n 9

5)

Lu

ng

and

Mal

e0.0

3 (

1 i

n 3

,357)

1.0

3 (

1 i

n 9

7)

2.5

2 (

1 i

n 4

0)

6.7

4 (

1 i

n 1

5)

7.9

1 (

1 i

n 1

3)

bron

chu

sFem

ale

0.0

3 (

1 i

n 2

,964)

0.8

2 (

1 i

n 1

21)

1.8

1 (

1 i

n 5

5)

4.6

1 (

1 i

n 2

2)

6.1

8 (

1 i

n 1

6)

Mel

anom

a M

ale

0.1

5 (

1 i

n 6

56)

0.6

1 (

1 i

n 1

64)

0.6

6 (

1 i

n 1

51)

1.5

6 (

1 i

n 6

4)

2.4

2 (

1 i

n 4

1)

of

the

skin

Fem

ale

0.2

6 (

1 i

n 3

89)

0.5

0 (

1 i

n 2

00)

0.3

4 (

1 i

n 2

97)

0.7

1 (

1 i

n 1

40)

1.6

3 (

1 i

n 6

1)

Non

-Hodgk

in

Mal

e0.1

3 (

1 i

n 7

60)

0.4

5 (

1 i

n 2

22)

0.5

7 (

1 i

n 1

74)

1.6

1 (

1 i

n 6

2)

2.1

9 (

1 i

n 4

6)

lym

ph

om

aFem

ale

0.0

8 (

1 i

n 1

,212)

0.3

2 (

1 i

n 3

12)

0.4

5 (

1 i

n 2

21)

1.3

3 (

1 i

n 7

5)

1.8

7 (

1 i

n 5

3)

Pro

stat

eM

ale

0.0

1 (

1 i

n 1

0,5

53)

2.5

4 (

1 i

n 3

9)

6.8

3 (

1 i

n 1

5)

13.3

6 (

1 i

n 7

)16.7

2 (

1 i

n 6

)

Ute

rin

e ce

rvix

Fem

ale

0.1

6 (

1 i

n 6

38)

0.2

8 (

1 i

n 3

59)

0.1

3 (

1 i

n 7

50)

0.1

9 (

1 i

n 5

23)

0.7

0 (

1 i

n 1

42)

Ute

rin

e co

rpu

sFem

ale

0.0

6 (

1 i

n 1

,569)

0.7

1 (

1 i

n 1

42)

0.7

9 (

1 i

n 1

26)

1.2

3 (

1 i

n 8

1)

2.4

5 (

1 i

n 4

1)

*For

peo

ple

fre

e of

can

cer

at b

egin

nin

g of

age

inte

rval

.†A

ll s

ites

excl

ude

basa

l an

d s

qu

amou

s ce

ll s

kin

can

cers

an

d i

n s

itu

can

cers

exce

pt

uri

nar

y bl

adder

.‡In

clu

des

in

vasi

ve a

nd i

n s

itu

can

cer

case

s.

So

urc

e: D

evC

an:

Pro

babi

lity

of

Dev

elopin

g or

Dyi

ng

of

Can

cer

Soft

war

e, V

ersi

on

6.2

.1.

Sta

tist

ical

Res

earc

h a

nd A

pplica

tion

s B

ran

ch,

Nat

ion

alC

ance

r In

stit

ute

, 2007.

ww

w.s

rab.

can

cer.

gov/

dev

can

.R

epro

du

ced w

ith

per

mis

sion

fro

m:

Am

eric

an C

ance

r Soci

ety.

Can

cer

Fac

ts a

nd

Fig

ure

s 20

08.

Atl

anta

: A

mer

ican

Can

cer

Soci

ety,

In

c.

9781405156066_4_001.qxd 9/29/09 11:29

. . . .

Table 1.4 Cancer incidence and mortality rates* by site, race, and ethnicity, USA, 2000–2004

White African Asian American American Indian Hispanic/American and Pacific and Alaska Latino‡§¶

Islander Native†

IncidenceAll sites

Males 556.7 663.7 359.9 321.2 421.3Females 423.9 396.9 285.8 282.4 314.2

Breast (female) 132.5 118.3 89.0 69.8 89.3Colon and rectum

Males 60.4 72.6 49.7 42.1 47.5Females 44.0 55.0 35.3 39.6 32.9

Kidney and renal pelvisMales 18.3 20.4 8.9 18.5 16.5Females 9.1 9.7 4.3 11.5 9.1

Liver and bile ductMales 7.9 12.7 21.3 14.8 14.4Females 2.9 3.8 7.9 5.5 5.7

Lung and bronchusMales 81.0 110.6 55.1 53.7 44.7Females 54.6 53.7 27.7 36.7 25.2

Prostate 161.4 255.5 96.5 68.2 140.8Stomach

Males 10.2 17.5 18.9 16.3 16.0Females 4.7 9.1 10.8 7.9 9.6

Uterine cervix 8.5 11.4 8.0 6.6 13.8

MortalityAll sites

Males 234.7 321.8 141.7 187.9 162.2Females 161.4 189.3 96.7 141.2 106.7

Breast (female) 25.0 33.8 12.6 16.1 16.1Colon and rectum

Males 22.9 32.7 15.0 20.6 17.0Females 15.9 22.9 10.3 14.3 11.1

Kidney and renal pelvisMales 6.2 6.1 2.4 9.3 5.4Females 2.8 2.8 1.1 4.3 2.3

Liver and bile ductMales 6.5 10.0 15.5 10.7 10.8Females 2.8 3.9 6.7 6.4 5.0

Lung and bronchusMales 72.6 95.8 38.3 49.6 36.0Females 42.1 39.8 18.5 32.7 14.6

Prostate 25.6 62.3 11.3 21.5 21.2Stomach

Males 5.2 11.9 10.5 9.6 9.1Females 2.6 5.8 6.2 5.5 5.1

Uterine cervix 2.3 4.9 2.4 4.0 3.3

*Per 100,000, age adjusted to the 2000 US standard population.†Data based on Contract Health Service Delivery Areas (CHSDA), 624 counties comprising 54% of the US AmericanIndian/Alaska Native population; for more information, please see: Espey DK, Wu XC, Swan J, et al. Annual report to thenation on the status of cancer, 1975–2004, featuring cancer in American Indians and Alaska Natives.‡Persons of Hispanic/Latino origin may be of any race.§Incidence data unavailable from the Alaska Native Registry and Kentucky.¶Matality data unavailable from Minnesota, New Hampshire, and North Dakota.

Source: Ries LAG, Melbert D, Krapcho M, et al. (eds.). SEER Cancer Statistics Review, 1975–2004, National Cancer Institute,Bethesda, MD, www.seer.cancer.gov/csr/1975_2004/, 2007.Reproduced with permission from: American Cancer Society. Cancer Facts and Figures 2008. Atlanta: American Cancer Society, Inc.

9781405156066_4_001.qxd 9/29/09 11:29

stereotyped, communicating with difficulty due to language barriers, dis-trusting the medical establishment, and not having health insurance, allof which can hinder the prevention, early detection, and successful treat-ment. These factors, however, do not always explain the disparities incancer risks and prevalence rates. Cultural and genetic differences thatexist may also increase or reduce the risk of developing cancer and thesewill be examined in subsequent chapters.

Environment and lifestyle choices affect the risk of cancer development

Many cases of cancer have been linked to the environment, either by adirect result of lifestyle or from exposure to carcinogens. For example,among the thousands of chemical compounds in cigarette smoke, morethan 40 are known carcinogens. It is well-established that the use of

tobacco products or exposure to second-hand smoke in the environment drasticallyincreases a person’s risk of developinglung and oral cancer. Smoking has also been demonstrated to contribute tokidney, pancreatic, cervical, and stomachcancers as well as acute myeloid leukemia.Another example is the risk of skin cancerfrom exposure to the sun’s ultraviolet(UV) light.1.4 UV radiation damages andmutates DNA, which can significantlycompromise the workings of a cell. Thecorrelation between carcinogen exposureand cancer development implies thatmany cancers are preventable. It is the goalthat with improved education, changes inlifestyles, the use of proper precautions,and implementation of environmentalregulations that there will be a decreasein the number of new cancer cases.

Health disparities exist for many diseases

Unfortunately, those most frequently burdened by cancer and othercatastrophic illnesses are oftentimes those who are least capable of

coping with them. People with lowincomes often lack health insurance andtraditionally have less access to qualitymedical care. As a consequence, the poorand uninsured are less likely to receivequality treatment and services, are more


. . . .

1.4 Generations ago, people believedextensive sunlight exposure was anindicator of low social class, since hav-ing a tan was an indication of beinga day laborer who worked outside. Thedawn of commercial air travel madeit easier for the wealthy to visit beachresorts for extended winter vacationsand eventually the “healthy glow” ofa tan was associated with wealth.

?Name three environmentalcauses of cancer and whatcould be done to reverse therisk in each case.

?Why would a person be morelikely to die from cancer if it was detected at a later stage?

9781405156066_4_001.qxd 9/29/09 11:29

. .

likely to be treated for cancer at a later stage of the disease, and are thusmore likely to die from the disease.

WILL CANCER BE CONQUERED WITHIN OUR LIFETIME?

The number of cancer survivors increases with each passing year; someare deemed cancer-free while others continue to undergo treatment fortheir disease. The five-year relative survival rate for all cancers diagnosedbetween 1991 and 2001 was 66%, which is significantly higher than thedocumented rate of 50% from 1974 to 1976 (Table 1.5). This rate increaseis certainly an encouraging sign. Nevertheless, not all cancers are the sameand each type has its own mortality and survival statistics. The prognosisfor recovery for particular cancers will be discussed in later chapters.

Cancer is not an automatic death sentence

It is important to stress the fact that many people not only survive theirbattle with cancer but thrive and live normal lives. The NCI has set anambitious goal for the elimination of suffering and death due to cancer bythe year 2015, hoping that cancer will be considered a chronic diseaseby then. Former NCI director Dr Andrew C. von Eschenbach said that theestablishment of this goal did not mean that cancer would be “cured,”but that many cancers could be eliminated and others controlled at accept-able levels. He referred to this as the 3-D approach to cancer research:Discovery – the process of generating new information at the genetic, molecu-lar, cellular, individual, and population levels.Development – the improvement of cancer detection, diagnosis, predictions,treatments, and prevention.Delivery – the method of distributing cancer interventions to everyonethrough means of research, communication, education and training, andtechnical assistance.If this goal becomes a reality, the effects on millions of people and their fam-ilies would be stunning. The three words “You have cancer” will have a farless dramatic impact, and the fear and ignorance associated with the diseasewill be significantly diminished. Without question, this goal is an extremelyambitious one, but it is filled with much promise and hope and its achieve-ment would be an extraordinary milestone in the course of medical science.

EXPAND YOUR KNOWLEDGE

1 A myosarcoma would originate in what type of tissue?2 A study that was done concluded that men possessing certain versionsof two genes have a predisposition for the development of testicular


. .

9781405156066_4_001.qxd 9/29/09 11:29


. . . .

Tab

le 1

.5T

ren

ds

in 5

-yea

r re

lati

ve

surv

ival

rat

es*

(%)

by

rac

e an

d y

ear

of

dia

gno

sis,

U

S,

1975

–200

3

Wh

ite

Afr

ican

Am

eric

anA

ll r

aces

Sit

e19

75–7

719

84–8

619

96–2

003

1975

–77

1984

–86

1996

–200

319

75–7

719

84–8

619

96–2

003

All s

ites

51

55

67

†40

41

57

†50

54

66

†

Bra

in23

28

34

†27

33

37

†24

29

35

†

Bre

ast

(fem

ale)

76

80

90

†62

65

78

†75

79

89

†

Colo

n52

60

66

†46

50

55

†51

59

65

†

Eso

ph

agu

s6

11

18

†3

811

†5

10

16

†

Hodgk

in l

ymph

om

a74

80

87

†71

75

81

†74

79

86

†

Kid

ney

51

56

66

†50

54

66

†51

56

66

†

Lar

ynx

67

68

66

59

53

50

67

66

64

Leu

kem

ia36

43

51

†34

34

40

35

42

50

†

Liv

er#

46

10

†2

57

†4

611

†

Lu

ng

and b

ron

chu

s13

14

16

†12

11

13

†13

13

16

†

Mel

anom

a of

the

skin

82

87

92

†60

†70

§77

82

87

92

†

Mye

lom

a25

27

34

†31

32

32

26

29

34

†

Non

-Hodgk

in l

ymph

om

a48

54

65

†49

48

56

48

53

64

†

Ora

l ca

vity

55

57

62

†36

36

41

53

55

60

†

Ova

ry37

39

45

†43

41

38

37

40

45

†

Pan

crea

s3

35

†2

55

†2

35

†

Pro

stat

e70

77

99

†61

66

95

†69

76

99

†

Rec

tum

49

58

66

†45

46

58

†49

57

66

†

Sto

mac

h15

18

22

†16

20

24

†16

18

24

†

Tes

tis

83

93

96

†82

‡87

‡88

83

93

96

†

Th

yroid

93

94

97

†91

90

94

93

94

97

†

Uri

nar

y bl

adder

75

79

81

†51

61

65

†74

78

81

†

Ute

rin

e ce

rvix

71

70

74

†65

58

66

70

68

73

†

Ute

rin

e co

rpu

s89

85

86

†61

58

61

88

84

84

†

*Su

rviv

al i

s ad

just

ed f

or

norm

al l

ife

expec

tan

cy a

nd b

ased

on

cas

es d

iagn

ose

d i

n t

he

SE

ER

9 a

reas

fro

m 1

975–1

977,

1984–1

986,

and 1

996–2

003,

and f

ollo

wed

th

rou

gh 2

004.

†Th

e dif

fere

nce

in

rat

es b

etw

een

1975–1

977 a

nd 1

996–2

003 i

s st

atis

tica

lly

sign

ifica

nt

(N<

0.0

5).

‡Th

e st

andar

d e

rror

of

the

surv

ival

rat

e is

bet

wee

n 5

an

d 1

0 p

erce

nta

ge p

oin

ts.

§Th

e st

andar

d e

rror

of

the

surv

ival

rat

e is

gre

ater

th

an 1

0 p

erce

nta

ge p

oin

ts.

#In

clu

des

in

trah

epat

ic b

ile

du

ct.

So

urc

e:R

ies

LA

G,

Mel

bert

D,

Kra

pch

o M

, et

al

(eds)

. SE

ER

Can

cer

Stat

isti

cs R

evie

w,

1975

–200

4. N

atio

nal

Can

cer

Inst

itu

te,

Bet

hes

da,

MD

,w

ww

.see

r.ca

nce

r.go

v/cs

r/1975_2

004/,

2007.

Rep

rodu

ced w

ith

per

mis

sion

fro

m:

Am

eric

an C

ance

r Soci

ety.

Can

cer

Fac

ts a

nd

Fig

ure

s 20

08.

Atl

anta

: A

mer

ican

Can

cer

Soci

ety,

In

c.

9781405156066_4_001.qxd 9/29/09 11:29

cancer that is higher than that for the general population. What wouldyou want to know about the study that would help determine how validthe conclusions are?3 Provide three reasons why the probabilities of developing cancer formen and women are different.4 Give some examples of what can be done about disparities in the health-care system today.5 Do you think irradiated food (i.e., food exposed to radiation to sterilizeit) is a potential cancer risk? Why or why not?

ADDITIONAL READINGS

American Cancer Society, Surveillance Research, 2007 & 2008. http://www.cancer.org/docroot/PRO_1_1_Cancer_Statistics_2008_Presentation.asp

Cancer and the Environment: What You Need to Know. What You Can Do. National CancerInstitute (NCI) and the National Institute of Environmental Health Sciences(NIEHS) NIH publication no. 03-2039, August 2003.

Closing In On Cancer, Solving a 5000-Year-Old Mystery. A Publication of the NationalCancer Institute, US Department of Health and Human Services, Public HealthService, National Institutes of Health.

Erikson, C., Salsberg, E., Forte, G., Bruinooge, S., and Goldstein, M. (2007) Futuresupply and demand for oncologists. Journal of Oncology Practice, 3: 79–86.

Farber, S., Diamond, L. K., Mercer, R. D., Sylvester, Jr, R. R., and Wolff, J. A.(1948) Temporary remissions in acute leukemia in children produced by folic acid antagonist . . . aminopterin. New England Journal of Medicine, 238:787–793.

National Institute for Occupational Safety and Health (NIOSH): www.cdc.gov/niosh/


. . . .

9781405156066_4_001.qxd 9/29/09 11:29

the basics of cancer copyrighted material · the basics of cancer ... a breast cancer can spread to...

Documents