cancer understanding risks and measures of prevention l.
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  2. INTRODUCTION • About 2 out of every 5 Americans will develop some type of cancer during their lifetime; about 1 in 5 will die from cancer (40% and 20%, respectively) • Most cancers are preventable • Cigarette smoke is estimated to cause about 30% of all forms of cancer • A healthy diet reduces the risk of cancer

  3. About 50% of cancer patients can be cured if their cancer is detected at an early stage • “Cured” means a person’s life expectancy is the same as a person who never had cancer • The American Cancer Society recommends watching for certain warning signs that indicate cancer may be developing • Change in a wart or mole • Hoarseness (persistent) • Difficulty in swallowing American Cancer Society

  4. Nagging cough • Thickening or lump • A sore that does not heal • Persistent indigestion • Unusual bleeding or discharge • Change in bowel or bladder functions

  5. UNDERSTANDING CANCER:Incidence of Various Cancers • Certain cancers in the U.S. have remained steady over the past 50 years for both men and women (esophagus, bladder, pancreas) • Stomach cancer has declined in both sexes; liver, uterine, and colon cancers have declined in women

  6. Unfortunately there has been an increase in lung cancer among both men and women • The major reason is cigarette smoking • In addition to lung cancer, increases are seen in breast, prostate, and skin cancers

  7. UNDERSTANDING CANCER:What is Cancer? • The term cancer comes from the Latin word meaning crab; cancer is now defined as the unregulated growth of specific cells in the body • Refers to over 100 different diseases • If a normal cell begins to grow abnormally and reproduces too rapidly, a mass of abnormal cells eventually develops a tumor

  8. If cells remain localized at the site of origin and if the cells multiply slowly, the tumor is referred to as a benign tumor • Cysts, warts, moles • Usually removed surgically and generally not a threat to life • Benign tumors can regrow • Malignant tumors are composed of cells that grow rapidly, have abnormal properties, and invade other normal cells • Malignant cells have altered shapes

  9. A pathologist (specializes in the causes of diseases) can determine whether the cells removed from a tumor are abnormal and to what degree • The cells of most malignant tumors undergo metastasis (a process where cells detach from the original tumor, enter the lymphatic system and bloodstream, and are carried to other organs)

  10. Cancers are medically classified according to the organ or tissue in which the tumor originates • Four major categories • Carcinomas (epithelial tissues, skin, nerves, breasts, etc..) • Sarcomas (connective tissues, bone, muscles, fat, and blood vessels) • Leukemias (organs and tissues that form blood cells) • Lymphomas (similar to leukemias) • About one-half of all human cancers originate in one of four organs: lungs, breast, prostate or colon

  11. Cancer develops over time • Cells of a tumor can be removed through a procedure called a biopsy

  12. UNDERSTANDING CANCER:Most Cancers are Not Inherited • Most scientific research indicates that 90 to 95% of all cancers (including breast, lung, stomach, colon, skin or prostate cancers) are not inherited from parents (except in a few families) • Genetic refers to genes that are changed in a person’s body cells; inherited means that defective genes were passed on

  13. ENVIRONMENTAL FACTORS IN CANCER • The risk factors associated with cancer are complex • It is difficult to pinpoint a single cause of cancer, but certain environmental factors are strongly associated with the occurrence of particular cancers • Cigarette smoking and lung cancer • Exposure to ultraviolet light and skin cancer

  14. Epidemiology is the branch of science that investigates the causes and frequencies of diseases in human populations • Epidemiological studies show that 80 to 90% of cancers are caused by exposure to environmental factors known to increase the risk of cancer

  15. There are 3 classes of environmental agents • Ionizing radiation • Tumor viruses • Chemical carcinogens • Each of these agents increases the risk of cancer by producing chemical agents in genes called mutations

  16. ENVIRONMENTAL FACTORS IN CANCER:Ionizing Radiation • Ionizing radiation consists of X-rays, UV light, and radioactivity whose energy damages cells and chromosomes • Because any amount of ionizing radiation, however small, has potential for causing damage one should minimize exposure to X-rays

  17. The most common source of radiation is the ultraviolet (UV) radiation in sunlight • The rate of skin cancers have increased over the years • Melanoma - is a dangerous form of skin cancer • The most common skin cancer is squamous cell carcinoma • UV radiation has two different wavelengths • UVA and UVB - both are harmful

  18. ENVIRONMENTAL FACTORS IN CANCER:Tumor Viruses • Only four tumor viruses have been identified with human cancers

  19. Increased cancer risk due to viruses occur with liver cancer (hepatitis B), genital cancer (papilloma virus), leukemia and lymphoma (human T-cell leukemia-lymphoma virus), and cancer of the nose in Africans (Epstein-Barr virus) • The causes for most cancers are in environmental factors rather than tumor viruses

  20. ENVIRONMENTAL FACTORS IN CANCER:Chemical Carcinogens • A chemical carcinogen is an environmental chemical that can interact with cells to initiate cancer (usually by altering the chromosomes or genes in the cells) • Many substances have been tested for carcinogenic elements; but many have not • Those we know of and should avoid include: cigarette smoke, pesticides, asbestos, heavy metals, benzene and nitrosamines

  21. REDUCING CANCER RISK: Reducing Risk of BreastCancer • There is a significant association between the rate of breast cancer and the amount of fat in the diet of people in various countries • Other risk factors associated with breast cancer include high radiation exposure, late child-bearing, late menopause, and high lifetime exposure to estrogen

  22. Early detection is the key • Regular breast self-examinations • The American Cancer Society recommends a screening mammogram by age 40 • Women 40-49 should get a mammogram every 1-2 years • Women over 50 should get a mammogram every year • The amount of X-rays in the mammogram are very low, and outweigh the possible risk of not detecting breast cancer early

  23. Men also get breast cancer, but the incidence is low • Xenoestrogens, which mimic the natural effects of estrogen in women, maybe one reason for the increase in breast cancer due to exposure to them

  24. REDUCING CANCER RISK:Reducing Risk of Testicular and Prostate Cancer • The rates of testicular and prostate cancer have been increasing, and like breast cancer the causes are unknown for the most part • Testicular cancer is rare but can occur in young men, which is why a testicular self-examination is important for early detection

  25. Prostate cancer generally occurs in men over 65 year of age • Early diagnosis is facilitated by two tests • Finger rectal exam by a physician, who can feel the prostate and determined if enlarged • Prostate-specific antigen (PSA) which detects a protein in the blood associated with abnormal growth of the prostate gland

  26. REDUCING CANCER RISK:Regulating Diet • Many studies show that diet is associated with cancer • Certain dietary choices may help prevent cancer; most of these help boost the immune system

  27. CONFRONTING CANCER:Cancer-Susceptibility Genes • Only about 5 to 10% of all cancers are due to heredity • Some people inherit cancer-susceptibility genes • A cancer-susceptibility gene makes a person more vulnerable to environmental factors that increase risk of cancer • Identification of cancer-susceptibility genes in people raises ethical issues

  28. CONFRONTING CANCER:Seeking Cancer Treatments • There are three medical treatments for cancer • Surgery - surgical removal of all or most of the tumor • Radiation therapy - X-rays or other forms of high energy radiation used to destroy cancer cells • Chemotherapy - use of toxic chemicals to kills cancer cells

  29. Cancer treatments today are not noticeably more successful than in the past; although there have been successes with childhood leukemia, testicular cancer, and Hodgkin’s disease

  30. CONFRONTING CANCER:Coping with a Diagnosis of Cancer • A diagnosis of cancer can raise serious problems for the patient, and family and friends • Coping can be difficult • Denial on patient’s part, or family’s part • Patient must have surgery or other treatment • Patient and family must face death

  31. Stress and emotional upset can depress the immune system • Mental relaxation techniques and focusing on images and suggestions can help the immune system fight and destroy cancer cells • The coping strategies for dealing with the emotional distress of many chronic, fatal illnesses are similar

  32. Coping with cancer requires conviction and courage • The patient must believe that a cure is possible

  33. HEALTH IN REVIEW • Cancer refers to a number of different diseases, all of which share the common property of abnormal, unregulated cell growth in the body. • Both breast and testicular self-examinations are positive means of early cancer detection. • The principal environmental agents that cause cancer are ionizing radiation, tumor viruses, and carcinogenic chemicals. BSE/TSE

  34. If everything known about cancer prevention were practiced, up to two-thirds of cancers would not occur; thus cancer is largely a preventable disease. • Only 5 to 10 percent of cancers are caused by genes that have been inherited. The genetic changes in body cells that result in cancer are not passed on to children, as these genetic changes have not occurred in sperm or eggs.

  35. The treatments for cancer include: surgery, radiation, and chemotherapy which are designed to destroy as many cancer cells as possible. • Recovery from cancer depends on good nutrition, positive attitudes, healing images, and medical treatment appropriate for the particular cancer. A healthy, active immune system also is an essential component in cancer prevention and recovery.

  36. Cigarette smoking is responsible for about one-third of all cancers and dietary deficiencies or excesses for about one-half. • Overexposure to sunlight causes skin cancer, which is increasing. • Significantly reducing cancer requires major changes in people’s life-styles, including more attention to a healthy diet, elimination of tobacco use, limiting alcohol consumption, and reducing exposures to intense sunlight and chemical carcinogens.