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Understanding Cancer Development: Incidence, Prevention, and Warning Signals

Learn about the development and incidence of cancer, guidelines for preventing it, and the warning signals to watch out for. Discover recommended checkups and ways to reduce your risk.

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Understanding Cancer Development: Incidence, Prevention, and Warning Signals

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  1. CHAPTER OUTLINE Chapter 12 Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Prevention

  2. Cancer: Group of diseases characterized by uncontrolled growth and spread of abnormal cells Benign: Noncancerous Malignant: Cancerous Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Key Terms

  3. Deoxyribonucleic acid (DNA): Genetic substance of which genes are made; molecule that contains cell’s genetic code Ribonucleic acid (RNA): Genetic material that guides the formation of cell proteins Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Key Terms

  4. Oncogenes: Genes that initiate cell division Suppressor genes: Genes that deactivate the process of cell division Angiogenesis: Formation of blood capillaries Metastasis: The movement of cells from one part of the body to another Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Key Terms

  5. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Development • More than 100 types of cancer can develop in the body • The process of cancer begins with an alteration in DNA • Within DNA are oncogenes and tumor suppressor genes, which normally work together to repair and replace cells • Defects in these genes ultimately allow the cell to grow into a tumor; defects are caused by • External factors such as radiation, chemicals, and viruses • Internal factors such as immune conditions, hormones, and genetic mutations • Cancer starts with the abnormal growth of one cell, which then can multiply into billions of cancerous cells

  6. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Development • A critical turning point in the development of cancer is when a tumor reaches about one million cells • At this stage, it is referred to as carcinoma in situ • An undetected tumor may go for months or years without any significant growth • While encapsulated, it does not pose a serious threat to human health • To grow, tumors require more oxygen and nutrients

  7. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Development • In time, a few cancer cells start producing chemicals that enhance angiogenesis (capillary or blood vessel formation into the tumor) • Angiogenesis is the precursor of metastasis • Through the new blood vessels formed by angiogenesis: • Cancerous cells break away from a malignant tumor • They migrate to other parts of the body • They can cause new cancers

  8. 12.4 How Cancer Starts and Spreads

  9. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Development • Once cancer cells metastasize, treatment becomes more difficult • Therapy can kill most cancer cells, but a few cells might become resistant to treatment • Treatment-resistant cells can grow into a new tumor that will not respond to the same treatment

  10. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Statistics • Cancer is the second leading cause of death in the U.S. • About 23% of all yearly deaths are caused by cancer • Aproximately 1 in 2 men and 1 in 3 women in the U.S. will develop cancer • More than 560,000 Americans die from cancer each year • More than 1.3 million new cases are diagnosed each year

  11. 12.5 Death Rates for Major Cancer Sites

  12. 12.5 Death Rates for Major Cancer Sites

  13. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Critical Thinking • Have you ever had or do you now have any family members with cancer? • Can you identify lifestyle or environmental factors as possible contributors to the disease? • If not, are you concerned about your genetic predisposition, and are you making lifestyle changes to decrease your risk?

  14. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer-Causing Factors • As much as 80% of all human cancer is related to lifestyle or environmental factors • Diet • Obesity • Tobacco use • Sedentary lifestyle • Excessive use of alcohol • Exposure to occupational hazards

  15. 12.7 Cancer-Causing Factors SOURCE: Harvard Center for Cancer Prevention. Causes of Human Cancer, Harvard Report on Cancer Prevention, 1 (1996).

  16. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Guidelines forPreventing Cancer • Get proper nutrition • Abstain from tobacco • Avoid excessive sun exposure • Monitor estrogen, radiation exposure, and potential occupational hazards • Engage in physical activity • Maintain recommended body weight

  17. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Dietary Guidelines • Predominately a vegetarian diet (high in fiber and low in fat) • Should include a variety of fruits and vegetables, in particular cruciferous vegetables • The use of tea, soy products, calcium, and omega-3 fats is encouraged • Adequate fiber intake is recommended (25 to 38 gr/day) • Protein intake should be kept within the recommended guidelines • Avoid salt-cured, smoked, and nitrite-cured foods (nitrite and nitrates are used to prevent the growth of harmful bacteria in processed meats but lead to the formation of nitrosamines, which cause stomach and esophageal cancers)

  18. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Dietary Guidelines • Alcohol, if used at all, should be consumed in moderation, 1 (women) to 2 (men) servings per day • Grilling of meats at high temperatures is discouraged • Consume ample amounts of fruits and vegetables which are high in antioxidants and phytochemicals • Antioxidants seem to • Absorb free radicals before they can cause damage • Interrupt the sequence of reactions once damage has begun • Phytochemicals (plant chemicals) seem to prevent cancer by blocking the formation of cancerous tumors and disrupting the process at almost every step of the way

  19. Lowering Cancer Risks

  20. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Abstain from Tobacco Use • The biggest carcinogenic exposure in the workplace is cigarette smoke • Of all cancers, at least 30% are tied to smoking, and 87% of lung cancers are linked to smoking • Use of smokeless tobacco increases the risk for mouth, larynx, throat, and esophageal cancers

  21. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Avoiding Excessive Sun • Excessive exposure to ultraviolet radiation (both UVB and UVA rays) contributes to skin cancer • 1 in every 6 Americans will develop some type of skin cancer • The most common sites of skin cancer are those areas exposed to the sun most often (face, neck, and back of the hands) • Nearly 90% of the almost 1 million yearly cases of basal cell or squamous cell skin cancers in the U.S. could be prevented by protecting the skin from the sun • Melanoma is the most deadly form of skin cancer, causing 7,600 yearly deaths

  22. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Avoiding Excessive Sun • Tanning of the skin is the body’s natural reaction to permanent damage from too much sun • Even small doses of sunlight add up to a greater risk for skin cancer and premature aging • Avoid sun exposure between 10:00 am and 4:00 pm • Sun lamps and tanning parlors provide mainly ultraviolet A rays (UVA) and have been linked to melanoma

  23. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Avoiding Excessive Sun • Apply sunscreen lotion about 30 minutes before lengthy exposure to the sun • A sun protection factor (SPF) of at least 15 is recommended • When swimming or sweating, reapply waterproof sunscreens often (sunscreens lose strength when diluted)

  24. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Critical Thinking • What significance does a “healthy tan” have in your social life? • Are you a “sun-worshiper,” or are you concerned about skin damage, premature aging, and potential skin cancer in your future?

  25. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Monitoring Estrogen, Radiation Exposure, & Potential Occupational Hazards • Use of estrogen therapy has been linked to endometrial cancer in some studies • Exposure to radiation increases the risk for cancer(use the lowest dose possible to keep cancer risk down) • Occupational hazards increase the risk for cancer • Examples include asbestos fibers, nickel and uranium dusts, chromium compounds, vinyl chloride, and bischlormethyl ether • Cigarette smoking magnifies the risk from occupational hazards

  26. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Maintain Physical Activity • An active lifestyle seems to have a protective effect against cancer • Cancer mortality in active men and women is lower • A daily 30-minute moderate-intensity exercise program lowers the risk for colon cancer and may lower the risk for cancers of the breast and reproductive system

  27. 11.9 Association between Physical Fitness and Cancer Mortality

  28. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Promoters • Physical inactivity • Being more than 10 pounds overweight • Frequent consumption of red meat • A diet high in fat • Charred/burned foods • Frequent consumption of nitrate/nitrite-cured, salt-cured, or smoked foods

  29. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Cancer Promoters • Alcohol consumption • Excessive sun exposure • Estrogens • Methyleugenol (flavoring agent in packaged foods) • Radon • Wood dust (high levels)

  30. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Warning Signals of Cancer • Change in bowel or bladder habits • Sore that does not heal • Unusual bleeding or discharge • Thickening or lump in breast or elsewhere • Indigestion or difficulty in swallowing • Obvious change in wart or mole • Nagging cough or hoarseness

  31. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Recommended Checkups • Include health counseling • Depending on age and gender, may include examinations for • cancers of the thyroid, oral cavity, skin, lymph nodes, testes, and ovaries • some nonmalignant diseases

  32. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Recommended Checkups • Breast checkup • Women 40 and older should • Have an annual mammogram • Have an annual clinical breast examination (CBE) • Optional breast self-examination (BSE) • Women 20–39 should • Have a clinical breast examination every 3 years • Optional BSE • Women at increased risk (family or personal history) should discuss frequency and additional testing with their doctors

  33. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Recommended Checkups • Colon & rectum checkup • Beginning at age 50 follow one of the examination schedules below: • Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) every year • Flexible sigmoidoscopy (FSIG) every 5 years • FOBT or FIT every year and FSIG every 5 years • Double-contrast barium enema every 5 years • Colonoscopy every 10 years

  34. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Recommended Checkups • Prostate checkup • Beginning at age 50, men with life expectancy of at least 10 years should have the choice of having these tests annually • A prostate-specific antigen (PSA) test • A digital rectal exam • Men at high risk (African-American and strong family history) should begin testing at age 45

  35. Cancer Development Incidence of Cancer Guidelines for Preventing Cancer Warning Signals of Cancer Recommended Checkups Recommended Checkups • Uterus checkup • Cervix: Three years after beginning of vaginal intercourse, but no later than 21, women should have a Pap test each year or a liquid-based test (less frequent after the age of 30 and following three consecutive tests with normal findings) • Endometrium: • At menopause all women should be informed about risks and symptoms and report unexpected bleeding or spotting to their doctors • Beginning at age 35, women with or at risk for hereditary nonpolyposis colon cancer should be offered an endometrial biopsy annually

  36. End of Chapter

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