chapter 16. leading cause of disease-related death among people under age 75 second leading cause...
TRANSCRIPT
Chapter 16
Cancer Leading cause of disease-related death
among people under age 75 Second leading cause of death Evidence supports that most cancers
could be prevented by simple lifestyle changes
Tobacco is responsible for about 30% of all cancer deaths
Poor diet and exercise habits account for another 30% of cancer deaths
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Figure 16.1 Percentage of all cancer deaths linked to risk factors
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What is Cancer? Definition: An abnormal and uncontrolled
growth of cells that can lead to death Tumor: A mass of tissue that serves no
physiological purposeBenign tumor: Mass of cells enclosed in a
membrane that prevents their penetration of other tissues
Malignant tumor: Can invade surrounding tissues
Every case of cancer begins as: a genetic change in a cell that allows it to grow and divide when it should not
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Figure 16.2 Tumor development occurs in stages
Metastasis Definition: The spread of cancer cells from one part of the body to another
Primary tumor: original location of cancer
Secondary tumors (metastases) : New tumors
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Stage Description
0 Early cancer, present only where it originated
I More extensive
II Greater tumor size
III Cancer has spread to nearby lymph nodes/adjacent organs
IV Advanced cancer; spread to other organs
Types of Cancer Classified according to types of cells
that give rise to themCarcinomas –Sarcomas –Lymphomas-Leukemias -
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The Incidence of Cancer American Cancer Society
Estimates:5-year survival rate for all cancers
diagnosed between 1995 and 2005 is 68% (excludes~ 1 million curable types of skin cancer)
At current rates, its estimated that1 in 2 men and 1 in 3 women will develop cancer during their lifetime
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The Incidence of Cancer
American Cancer Society Estimates:90% of skin cancer could have been
prevented by protecting the skin from the sun
87% of lung cancer could have been prevented by avoiding exposure to tobacco smoke
Regular screening and self-examinations could save an additional 100,000 lives per year
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Lung Cancer Most common cause of cancer related
death in the U.S.157,000 deaths
Risk factorsTobacco smoke (including ETS)
contributes to 90% of lung cancer deaths
Detection Difficult to detect earlySymptoms do not appear until invasive stageSymptoms: Persistent cough, chest pain, or
recurring bronchitisDiagnosis: CT scan (earlier?), chest x-ray or
sputum examination, bronchoscopy11
Lung Cancer Treatment
If caught early, localized cancers can be treated with surgery Only 15% detected prior to spreading so, Radiation and chemotherapy are used in
addition to surgery For cases detected early, 53% of patients
are alive 5 years post-diagnosisOverall, the 5-year survival rate is only
15%
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Colon and Rectal (Colorectal)Cancer
Third most common type of cancer Risk factors
Age (91% of cases occur in people 50 or older)
Heredity, genetic propensity to develop polyps
Diet, smoking, excessive alcohol use and obesity
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Detection and treatmentRegular screening tests are recommended beginning at age 50
Symptoms: bleeding from rectum and changes in bowel habits
Treatment Primarily SurgeryRadiation and chemotherapy can be used
Colon and Rectal Cancer
Breast Cancer Most common cancer in women
Causes almost as many deaths in women as lung cancer
Risk factorsStrong genetic factor:Age: Most common in women over 50
Early onset of menstruation First child after 30Current use of HTUnhealthy diet and lifestyle
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Breast Cancer Early detection
ACS recommends 1 mammogram/year (women over 40)
Clinical and Self breast exams (starting at age 20)
Symptoms may include a lump, changes in size, dimpled, redness or scaliness of nipple or breasts,
Treatment Ultrasonography and biopsy to
determine if cancerous If the tumor is discovered before
it has spread, patient has 98% chance of surviving more than 5 yrs.
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Breast Cancer
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Prostate Cancer Most common cancer in men
Risk factors Age( more than 60% of cases diagnosed in men over 65)
Genetic predispositionDiet and Lifestyle African American and Jamaican men have highest rates in the world
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Prostate Cancer Detection
Blood test: Prostate-specific antigen (PSA)
Rectal exam:Symptoms may include changes in urinary frequency, weak/interrupted urine flow, painful urination and blood in urine
Treatment Surgical removal of the prostate and radiation (depends on stage and age)
Radioactive seeds5-year survival rate is nearly 100%
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Cancers of the Female Reproductive Tract
Cervical cancer Most cases stem from human papillomavirus (HPV) infection (STD)
PreventionThe PAP test is a highly effective
screening test for this cancer All sexually active women ages 18-
65 should be tested regularly Gardasil
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Skin Cancer Types of skin cancer
Basal cell carcinomasSquamous cell carcinomasMelanoma (most serious type of skin cancer
Most common form of cancer1 million cases per year (68,000 are melanoma)
Risk factorsExcessive exposure to UV raysCommon causes are sunburns and suntansCaucasians are 10X more likely than African
Americans to develop basal and squamous cell carcinoma
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PreventionAvoid long term overexposure to sunlight
Detection of MelanomaABCD screen test
Skin Cancer
The Causes of Cancer The role of DNA (Deoxyribonucleic acid)
Each cells has 23 pairs of chromosomes Gene: Smaller unit of DNA
DNA mutations and cancer Mutagens: Radiation, certain viruses and chemical
substances Oncogenes: A gene in which mutations are
associated with the transformation of a normal cell into a cancer cell
Tumor suppressor gene: Type of oncogene that normally restricts cellular growth
Hereditary cancer risks BRCA1 gene
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The Causes of Cancer Cancer promoters
Definition: Do not directly produce mutations, they instead accelerate the growth of cells without damaging or permanently altering the DNA Estrogen is an example
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Dietary Factors Food choices affect your cancer risk by:
exposing you to potentially dangerous compounds and depriving you of protective compounds
Dietary fat and meat Diets high in “bad” fats and meat may
contribute to colon, stomach, and prostate cancers
Omega-3 fats are healthier for body Alcohol
Risk of oral and colon cancer Fried foods Fiber Fruits and vegetables
Phytochemicals Inactivity and obesity
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Carcinogens in the Environment
MicrobesAbout 15% of the world’s cancers are caused
by microbes Ingested chemicals
Nitrosamines: Nitrates and nitrites found in processed meats that combine with dietary substances and become highly potent carcinogens
Environmental and industrial pollution Radiation
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Figure 16.8 The seven major warning signs of cancer
Preventing Cancer Lifestyle choices
Avoid tobaccoControl diet and weightRegular exerciseProtect skin from the sunAvoiding environmental and
occupational carcinogensFollow recommendations for cancer
screenings
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