global risk factors for cancer by salwa hassan teama m.d.n.c.i. cairo university, egypt

Global Risk Factors For Global Risk Factors For CancerCancer

ByBy

Salwa Hassan TeamaSalwa Hassan TeamaM.D.N.C.I. Cairo University, EgyptM.D.N.C.I. Cairo University, Egypt

ContentsContents CancerCancer Cancer as a Global Health ProblemCancer as a Global Health Problem Cancer As a Genetic DiseaseCancer As a Genetic Disease Risk FactorRisk Factor Global Risk Factor Of CancerGlobal Risk Factor Of Cancer Avoidable Cancer RiskAvoidable Cancer Risk Primary PreventionPrimary Prevention Early detection (Screening)Early detection (Screening) Genetic testingGenetic testing

CancerCancer

CancerCancer is one of the most common and severe is one of the most common and severe problems of clinical medicine. problems of clinical medicine.

CancerCancer is not a single disease but rather a is not a single disease but rather a name applied to a great variety of malignant name applied to a great variety of malignant tumor that are formed by the same basic tumor that are formed by the same basic process of uncontrolled growth.process of uncontrolled growth.

Cancer as a Global Health Cancer as a Global Health ProblemProblem

CancerCancer has emerged as a major has emerged as a major public health problem in developing public health problem in developing countries for the first time, matching countries for the first time, matching its effect in industrialized nationsits effect in industrialized nations. . This This is a global problem. is a global problem.

CancerCancerCancerCancer begins in begins in cellscells, , the building blocks that formthe building blocks that form tissues.tissues. Normally, cells grow and divide to form new cells as the body Normally, cells grow and divide to form new cells as the body needs themneeds them. . When cells grow old, they die, and new cells take When cells grow old, they die, and new cells take their place.their place. Sometimes, this orderly process goes wrongSometimes, this orderly process goes wrong. . New cells form New cells form when the body does not need them, and old cells do not diewhen the body does not need them, and old cells do not die. . These extra cells can form a mass of tissue called a growth orThese extra cells can form a mass of tissue called a growth or tumor.tumor.

Cancer

Cancer

CancerCancer Cell proliferation results in a mass (neoplasm or Cell proliferation results in a mass (neoplasm or

tumor) that invade neighboring tissues and may tumor) that invade neighboring tissues and may metastasize to more distant sites. The growth is metastasize to more distant sites. The growth is autonomous, increasingly malignant, and if left autonomous, increasingly malignant, and if left untreated, invariably fatal.untreated, invariably fatal.

Early diagnosis and early treatment are vital, and Early diagnosis and early treatment are vital, and identification of persons at increased risk of cancer identification of persons at increased risk of cancer before its development is an important objective of before its development is an important objective of cancer research.cancer research.

CancerCancer

The etiology of cancer is The etiology of cancer is multifactorial,multifactorial, with genetic, with genetic, environmental, medical, and lifestyle factors environmental, medical, and lifestyle factors interacting to produce a given malignancyinteracting to produce a given malignancy..

Knowledge of Knowledge of cancer geneticscancer genetics is rapidly improving our is rapidly improving our

understanding of cancer biology, helping to identify atunderstanding of cancer biology, helping to identify at--risk individuals, this expanding knowledge base has risk individuals, this expanding knowledge base has implications for all aspects of cancer management, implications for all aspects of cancer management, including prevention, screening, and treatment.including prevention, screening, and treatment.

Cancer As a Genetic Cancer As a Genetic DiseaseDisease

It is now believed that It is now believed that cancercancer is caused by is caused by geneticgenetic mutationsmutations most often, by a series of mutations, some most often, by a series of mutations, some of which may be inherited.of which may be inherited.

Certain normal genes involved inCertain normal genes involved in cellcell growth, growth, development, and differentiation can be converted into development, and differentiation can be converted into cancercancer--causingcausing " "oncogenesoncogenes" " by mutationby mutation. . Other genes Other genes that normally prevent the uncontrolled growth of cells that normally prevent the uncontrolled growth of cells ""suppressorsuppressor" " genes can also produce genes can also produce cancercancer if they if they areare knocked outknocked out by genetic mutations.by genetic mutations.

Cancer As a Genetic Cancer As a Genetic DiseaseDisease

Single mutations are generally not sufficient to Single mutations are generally not sufficient to cause cancer, but they produce changes that cause cancer, but they produce changes that may predispose cells to malignant growthmay predispose cells to malignant growth. . Additional mutations in other genes, caused by Additional mutations in other genes, caused by damage from the environment, continue the damage from the environment, continue the cells' malignant transformationcells' malignant transformation. . Thus, cancer is Thus, cancer is a multia multi--step process involving the interaction step process involving the interaction between genes and their environment.between genes and their environment.

www.accessexcellence.org/.../genes-cancer.gif

In the year 2000, malignant tumors were In the year 2000, malignant tumors were responsible for 12 percent of the nearly 56 responsible for 12 percent of the nearly 56 million deaths worldwide from all causesmillion deaths worldwide from all causes. . In many countries, more than a quarter of In many countries, more than a quarter of deaths are attributable to cancerdeaths are attributable to cancer. . In 2000, In 2000, 5.3 million men and 4.7 million women 5.3 million men and 4.7 million women developed a malignant tumor and developed a malignant tumor and altogether 6.2 million died from the altogether 6.2 million died from the diseasedisease. .

Cancer as a Global Health Cancer as a Global Health ProblemProblem

The predicted sharp increase in new The predicted sharp increase in new cases from 10 million new cases globally cases from 10 million new cases globally in 2000, to 15 million in 2020 will mainly in 2000, to 15 million in 2020 will mainly be due to steadily ageing populations in be due to steadily ageing populations in both developed and developing countries both developed and developing countries and also to current trends in smoking and also to current trends in smoking prevalence and the growing adoption of prevalence and the growing adoption of unhealthy lifestyles.unhealthy lifestyles.

Cancer as a Global Health ProblemCancer as a Global Health Problem

Risk FactorRisk Factor

A A risk factorrisk factor is anything that increases a is anything that increases a person's chance of getting a diseaseperson's chance of getting a disease. . Some Some risk factorsrisk factors can be changed, and others can be changed, and others cannotcannot. . Risk factorsRisk factors for for cancercancer can include a can include a person's age, sex, and family medical historyperson's age, sex, and family medical history. . Others are linked to cancerOthers are linked to cancer--causing factors in causing factors in the environmentthe environment. . Still others are related to Still others are related to lifestyle choices such as tobacco and alcohol lifestyle choices such as tobacco and alcohol use, diet, and sun exposure.use, diet, and sun exposure.


CancersCancers of the lung, mouth, larynx, bladder, of the lung, mouth, larynx, bladder, kidney, cervix, esophagus, and pancreaskidney, cervix, esophagus, and pancreas are are related to tobacco use, including cigarettes, related to tobacco use, including cigarettes, cigars, chewing tobacco, and snuffcigars, chewing tobacco, and snuff. . Smoking Smoking alone causes onealone causes one--third of all cancer deaths.third of all cancer deaths.

Skin cancerSkin cancer is related to unprotected is related to unprotected

exposure to strong sunlight.exposure to strong sunlight.


Breast cancer riskBreast cancer risk factors include several factors include several factorsfactors: : age; changes in hormone levels age; changes in hormone levels throughout life, such as age at first throughout life, such as age at first menstruation, number of pregnancies, and age menstruation, number of pregnancies, and age at menopause; obesity; and physical activityat menopause; obesity; and physical activity. . Also, women with a mother or sister who have Also, women with a mother or sister who have had breast cancer are more likely to develop had breast cancer are more likely to develop the disease. the disease.

ProstateProstate cancer risk cancer risk factors include factors include Age, race, and dietAge, race, and diet Older ageOlder age Prostate cancer is more common among Prostate cancer is more common among

AfricanAfrican--American men than among white menAmerican men than among white men. . HighHigh--fat diet fat diet Men with a father or brother who have had Men with a father or brother who have had

prostate cancer are more likely to get it.prostate cancer are more likely to get it.


Global Risk Factor Of CancerGlobal Risk Factor Of Cancer

• Old ageOld age• Environmental factors, defined broadly to include tobacco use, diet, infectious Environmental factors, defined broadly to include tobacco use, diet, infectious

diseases and sunlight.diseases and sunlight. Unhealthy lifestyle (Unhealthy lifestyle (Western lifestyleWestern lifestyle) Poor diet, lack of physical activity, or ) Poor diet, lack of physical activity, or

being overweightbeing overweight Occupational carcinogensOccupational carcinogens RadiationRadiation Chemicals and other substanceChemicals and other substance ObesityObesity Family history of cancer (Genetic susceptibility)Family history of cancer (Genetic susceptibility) AlcoholAlcohol In the gastroIn the gastro--intestinal tract intestinal tract ((GITGIT)), any chronic tissue damage with necrosis , any chronic tissue damage with necrosis

and regeneration carries an in creased cancer risk, eand regeneration carries an in creased cancer risk, e..gg. . consumption of very consumption of very hot beverages hot beverages ((squamous cell carcinoma of the esophagussquamous cell carcinoma of the esophagus)), gastro, gastro--oesophageal reflux oesophageal reflux ((adenocarcinoma of the esophagusadenocarcinoma of the esophagus)), chronic gastritis , chronic gastritis induced by Hinduced by H. . pylori infection pylori infection ((stomach cancerstomach cancer)), Crohn’s disease , Crohn’s disease ((cancer of cancer of the small intestinesthe small intestines) ) and ulcerative colitis and ulcerative colitis ((colon cancer)colon cancer)


Many of these risk factors can be avoided. Many of these risk factors can be avoided. Others, such as family history, cannot be Others, such as family history, cannot be avoided. People can protect themselves avoided. People can protect themselves by staying away from known risk factors by staying away from known risk factors whenever possible. whenever possible.


AgingAgingThe most important risk factor for cancer is The most important risk factor for cancer is

getting oldergetting older. . Most cancers occur in people Most cancers occur in people over the age of 65over the age of 65. . But people of all ages, But people of all ages, including children, can get cancer, tooincluding children, can get cancer, too ..…………..…………..


Tobacco SmokingTobacco Smoking Tobacco use is the most preventable cause of deathTobacco use is the most preventable cause of death. . Using tobacco products or regularly being around Using tobacco products or regularly being around

tobacco smoke tobacco smoke ((environmental or secondhand smokeenvironmental or secondhand smoke) ) increases the risk of cancer.increases the risk of cancer.

Smokers are more likely than nonsmokers to develop Smokers are more likely than nonsmokers to develop cancer. cancer.

People who use smokeless tobacco People who use smokeless tobacco ((snuff or chewing snuff or chewing tobaccotobacco) ) are at increased risk of cancer of the mouth.are at increased risk of cancer of the mouth.


SunlightSunlightUltraviolet Ultraviolet ((UVUV) ) radiationradiation comes from the sun, comes from the sun,

sunlamps, and tanning boothssunlamps, and tanning booths. . It causes early It causes early aging of the skin and skin damage that can lead aging of the skin and skin damage that can lead to skin cancer.to skin cancer.


Poor Diet, Lack of Physical Activity, Poor Diet, Lack of Physical Activity, or Being Overweight Peopleor Being Overweight People may be at may be at increased risk of several types of cancerincreased risk of several types of cancer. . For For example, studies suggest that people whose diet is example, studies suggest that people whose diet is high in fat have an increased risk of cancers of the high in fat have an increased risk of cancers of the colon, uterus, and prostatecolon, uterus, and prostate. . Lack of physical activity Lack of physical activity and being overweight are risk factors for cancers of and being overweight are risk factors for cancers of the breast, colon, esophagus, kidney, and uterus. the breast, colon, esophagus, kidney, and uterus. Choose a diet rich in Choose a diet rich in fruitsfruits and and vegetables.vegetables.


Being infected with certain viruses or bacteria may increase the risk of Being infected with certain viruses or bacteria may increase the risk of developing cancerdeveloping cancer: :

Human Human papillomavirusespapillomaviruses : : HPV infection is the main cause of cervical HPV infection is the main cause of cervical cancercancer. . It also may be a risk factor for other types of cancer.It also may be a risk factor for other types of cancer.

Hepatitis BHepatitis B andand hepatitis Chepatitis C virusesviruses: : Liver cancer can develop after many Liver cancer can develop after many years of infection with hepatitis B or hepatitis C.years of infection with hepatitis B or hepatitis C.

Human THuman T--cell leukemiacell leukemia//lymphoma viruslymphoma virus HTLV-1HTLV-1 : : Infection with HTLV-1 Infection with HTLV-1 increases a person's risk of lymphoma and leukemia.increases a person's risk of lymphoma and leukemia.

Human immunodeficiency virusHuman immunodeficiency virus HIVHIV : : HIV is the virus that causesHIV is the virus that causes AIDSAIDS. . People who have HIV infection are at greater risk of cancer, such as People who have HIV infection are at greater risk of cancer, such as lymphoma and a rare cancer calledlymphoma and a rare cancer called Kaposi's sarcomaKaposi's sarcoma..

EpsteinEpstein--Barr virusBarr virus EBVEBV : : Infection with EBV has been linked to an increased Infection with EBV has been linked to an increased risk of lymphoma.risk of lymphoma.

Human Human herpesvirusherpesvirus 8 8 HHV8HHV8 : : This virus is a risk factor for Kaposi's sarcoma.This virus is a risk factor for Kaposi's sarcoma. Helicobacter pyloriHelicobacter pylori : : This bacterium can cause stomach ulcersThis bacterium can cause stomach ulcers. . It also can It also can

cause stomach cancer and lymphoma in the stomach lining.cause stomach cancer and lymphoma in the stomach lining.

The The Western lifestyleWestern lifestyle and its health risks and its health risks::

The The Western lifestyleWestern lifestyle is characterized by a is characterized by a highly caloric diet, rich in fat, refined highly caloric diet, rich in fat, refined carbohydrates and animal protein, combined carbohydrates and animal protein, combined with low physical activity, resulting in an overall with low physical activity, resulting in an overall energy imbalanceenergy imbalance. . It is associated with a It is associated with a multitude of disease conditions, including multitude of disease conditions, including obesity, diabetes, cardiovascular disease, obesity, diabetes, cardiovascular disease, arterial hypertension and cancer.arterial hypertension and cancer.



Ionizing RadiationIonizing Radiation Ionizing radiation can cause cell damage that leads Ionizing radiation can cause cell damage that leads

to cancerto cancer. .

Certain Chemicals and Other SubstancesCertain Chemicals and Other Substances People who have certain jobs People who have certain jobs ((such as painters, such as painters,

construction workers, and those in the chemical construction workers, and those in the chemical industryindustry) ) have an increased risk of cancerhave an increased risk of cancer. . Many Many studies have shown that exposure to asbestos, studies have shown that exposure to asbestos, benzene, benzidine, cadmium, nickel, or vinyl benzene, benzidine, cadmium, nickel, or vinyl chloride in the workplace can cause cancer.chloride in the workplace can cause cancer.


Certain HormonesCertain Hormones Recommendation of hormonesRecommendation of hormones estrogenestrogen alone or alone or

estrogen along withestrogen along with progestinprogestin to help control problems to help control problems ((such as hot flashes, vaginal dryness, and thinning such as hot flashes, vaginal dryness, and thinning bonesbones) ) that may occur duringthat may occur during menopausemenopause. . However, However, studies show thatstudies show that menopausal hormone therapymenopausal hormone therapy can can cause seriouscause serious side effectsside effects . . Hormones may increase Hormones may increase the risk of breast cancer, heart attack, stroke, or blood the risk of breast cancer, heart attack, stroke, or blood clots.clots.

ObesityObesity is spreading epidemically is spreading epidemically throughout the worldthroughout the world. . It visualizes a It visualizes a chronic energy imbalance and is an chronic energy imbalance and is an independent predictor of an increased independent predictor of an increased cancer risk, particularly for carcinomas of cancer risk, particularly for carcinomas of the uterine endometrium, kidney and gall the uterine endometrium, kidney and gall bladder.bladder.



Family History of CancerFamily History of CancerMost Most cancerscancers develop because of changes develop because of changes

mutationsmutations inin genesgenes. . A normal cell may become A normal cell may become a cancer cell after a series of gene changes a cancer cell after a series of gene changes occuroccur. .

Some gene changes that increase the risk of Some gene changes that increase the risk of

cancercancer are passed from parent to child are passed from parent to child. . These These changes are present at birth in all cells of the changes are present at birth in all cells of the body.body.


AlcoholAlcoholHaving more than two drinks each day for many Having more than two drinks each day for many

years may increase the chance of developing years may increase the chance of developing cancerscancers of the mouth, throat, esophagus, of the mouth, throat, esophagus, larynx, liver, and breastlarynx, liver, and breast. . The risk increases with The risk increases with the amount of alcohol that a person drinksthe amount of alcohol that a person drinks.. The The risk is higher for a drinker who uses tobacco.risk is higher for a drinker who uses tobacco.

The aim of The aim of cancer controlcancer control is a reduction in is a reduction in both the incidence of the disease and the both the incidence of the disease and the associated morbidity and mortality, as well associated morbidity and mortality, as well as improved life for cancer patients and as improved life for cancer patients and their familiestheir families. . In addition to substantial In addition to substantial opportunities for primary prevention. opportunities for primary prevention.

Cancer control strategiesCancer control strategies

The best possible prevention against cancer remains The best possible prevention against cancer remains the avoidance of exposure to cancerthe avoidance of exposure to cancer--causing agentscausing agents: : this is called this is called primary preventionprimary prevention ((e.g. tobacco, e.g. tobacco, industrial carcinogens, etcindustrial carcinogens, etc ….)….)

Reduction of tobacco consumptionReduction of tobacco consumption. . It remains the It remains the most important avoidable cancer riskmost important avoidable cancer risk. . In the 20th In the 20th century, approximately 100 million people died worldcentury, approximately 100 million people died world--wide from tobaccowide from tobacco--associated diseasesassociated diseases ..

Avoidable Cancer RiskAvoidable Cancer RiskPrimary PreventionPrimary Prevention

Avoidable Cancer RiskAvoidable Cancer Risk

Having a healthy diet, being physically active, and maintaining a Having a healthy diet, being physically active, and maintaining a healthy weight may help reduce healthy weight may help reduce cancer riskcancer risk. .

Eat wellEat well:: A healthy diet includes plenty of foods that are high A healthy diet includes plenty of foods that are high

in fiber, vitamins, and mineralsin fiber, vitamins, and minerals. . This includes wholeThis includes whole--grain grain breads and cereals and 5 to 9 servings of fruits and vegetables breads and cereals and 5 to 9 servings of fruits and vegetables every dayevery day. . Also, a healthy diet means limiting foods high in fat Also, a healthy diet means limiting foods high in fat ((such as butter, whole milk, fried foods, and red meatsuch as butter, whole milk, fried foods, and red meat

. . Be active and maintain a healthy weightBe active and maintain a healthy weight:: Physical Physical

activity can help control your weight and reduce body fatactivity can help control your weight and reduce body fat.. Moderate physical activity Moderate physical activity ((such as brisk walkingsuch as brisk walking) ) for at least 30 for at least 30 minutes on 5 or more days each weekminutes on 5 or more days each week is recommended.is recommended.

Food Guide PyramidFood Guide Pyramid

Food Guide Food Guide PyramidPyramid

Avoidable Cancer RiskAvoidable Cancer RiskEarly DAETECTION Early DAETECTION (Screening)(Screening)

Early detection – the best strategy second Early detection – the best strategy second to primary prevention.to primary prevention.

Early detection through Early detection through screeningscreening, , particularly for cervical and breast particularly for cervical and breast cancers, allow for prevention and cancers, allow for prevention and successful cure.successful cure.

Screening and early detection Screening and early detection of cancerof cancer

Early detection of cancer greatly increases Early detection of cancer greatly increases the chances for successful treatmentthe chances for successful treatment

..There are two major components of There are two major components of

early detection of cancerearly detection of cancer: : education education to promote early diagnosis and to promote early diagnosis and screeningscreening..

Screening and early detection Screening and early detection of cancerof cancer

Recognizing possible warning signs of Recognizing possible warning signs of cancer cancer leads leads to early diagnosisto early diagnosis. . Increased awareness of possible Increased awareness of possible warning signs of cancer, among physicians, nurses warning signs of cancer, among physicians, nurses and other health care providers as well as among the and other health care providers as well as among the general public, can have a great impact on the general public, can have a great impact on the diseasedisease..

Some early signs of cancerSome early signs of cancer include lumps, sores that include lumps, sores that

fail to heal, abnormal bleeding, persistent indigestion, fail to heal, abnormal bleeding, persistent indigestion, and chronic hoarsenessand chronic hoarseness. . Early diagnosis is particularly Early diagnosis is particularly relevant for cancers of the breast, cervix, mouth, relevant for cancers of the breast, cervix, mouth, larynx, colon and rectum, and skinlarynx, colon and rectum, and skin..

The most successful is the early detection of The most successful is the early detection of cervical cervical cancer by cancer by cytologycytology and of and of breastbreast cancer by cancer by mammographymammography. .

ProstateProstate cancer screening by assessment of serum cancer screening by assessment of serum

PSAPSA levels may result in lower mortality rates.levels may result in lower mortality rates. For For coloncolon cancer, cancer, colonoscopycolonoscopy is considered the gold is considered the gold

standard although its application in populationstandard although its application in population--based based screening programs would require considerable screening programs would require considerable medical resources.medical resources.

Vaccinations :Vaccinations : HBV vaccination has already HBV vaccination has already been shown to prevent liver cancer in highbeen shown to prevent liver cancer in high--incidence countries and it is likely that human incidence countries and it is likely that human papillomavirus papillomavirus ((HPVHPV) ) vaccination will become a vaccination will become a reality in 3 to 5 yearsreality in 3 to 5 years..



GGenetic testingenetic testing. These tests can check for . These tests can check for certain inherited gene changes that increase certain inherited gene changes that increase the chance of developing the chance of developing cancercancer. . But inheriting But inheriting a gene change does not mean that you will a gene change does not mean that you will definitely develop definitely develop cancercancer. . It means that you It means that you have an increased chance of developing the have an increased chance of developing the disease.disease.

Genetic informationGenetic information : : Sources of genetic information Sources of genetic information include biologic samples ofinclude biologic samples of DNADNA, , information derived information derived from a person’s with a family history of disease. from a person’s with a family history of disease.

Family history may identify people with a modest to Family history may identify people with a modest to moderately increased risk of moderately increased risk of cancercancer or may serve as or may serve as the first step in the identification of an inherited the first step in the identification of an inherited cancercancer predisposition that confers a very high lifetime risk of predisposition that confers a very high lifetime risk of cancercancer. . For an increasing number of diseases, DNAFor an increasing number of diseases, DNA--based testing can be used to identify a specificbased testing can be used to identify a specific mutationmutation as the cause of inherited risk and to as the cause of inherited risk and to determine whether family members have inherited the determine whether family members have inherited the diseasedisease--related mutation.related mutation.

Avoidable Cancer Avoidable Cancer RiskRisk


Genetic testing Genetic testing Drawback:Drawback:

Psychological impactPsychological impact::First, there are the First, there are the emotions aroused by learning that one isemotions aroused by learning that one is or is or is not not likely to develop a serious diseaselikely to develop a serious disease. . Many Many people in disease families have already seen people in disease families have already seen close relatives fall victim to the disorderclose relatives fall victim to the disorder. . So So persons carry the disease gene can elicit persons carry the disease gene can elicit depression, even despair.depression, even despair.

School education programsSchool education programs for tobacco for tobacco hazards and healthy dietary habits, especially hazards and healthy dietary habits, especially because very few countries currently have because very few countries currently have effective education programseffective education programs. .

National cancer control programsNational cancer control programs can help to can help to

ensure that governments take the necessary ensure that governments take the necessary actions to guarantee that the public has the actions to guarantee that the public has the motivation to adopt healthy personal habits.motivation to adopt healthy personal habits.



New drugs will not necessarily New drugs will not necessarily eradicate tumors, but when used in eradicate tumors, but when used in combination with other agents, may combination with other agents, may turn many cases of rapidly fatal turn many cases of rapidly fatal cancer into ‘manageable’ chronic cancer into ‘manageable’ chronic illness. illness.

conclusionconclusion

Primary prevention by Primary prevention by avoidanceavoidance of risk factor , of risk factor , EducationEducation to promote to promote early early diagnosisdiagnosis and and screeningscreening are are the gold standard to decrease the gold standard to decrease cancer risk and benefit of all cancer risk and benefit of all humankind.humankind.

References & Online Further References & Online Further ReadingReading

http://www.who.int/topics/cancer/en/http://www.who.int/topics/cancer/en/ http://www.cancer.org/docroot/CRI/contenthttp://www.cancer.org/docroot/CRI/content http://www.cancer.gov/cancertopics/wyntk/overview/page4http://www.cancer.gov/cancertopics/wyntk/overview/page4 http://www.accessexcellence.org/AE/AEPC/NIH/gene13.htmlhttp://www.accessexcellence.org/AE/AEPC/NIH/gene13.html http://www.nci.nih.gov/cancertopics/pdq/genetics/overview/http://www.nci.nih.gov/cancertopics/pdq/genetics/overview/

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global risk factors for cancer by salwa hassan teama m.d.n.c.i. cairo university, egypt

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