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Cancer

Cancer . Ray M. Merrill, PhD, MPH Department of Health Science Brigham Young University. Did you know?. In the United States… 1 in 3 people will develop cancer in their lifetime 1 in 8 women will develop breast cancer in their lifetime

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Cancer

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  1. Cancer Ray M. Merrill, PhD, MPH Department of Health Science Brigham Young University

  2. Did you know? In the United States… • 1 in 3 people will develop cancer in their lifetime • 1 in 8 women will develop breast cancer in their lifetime • 1 in 6 men will develop prostate cancer in their lifetime • Over 1,400,000 people will be diagnosed with cancer this year • Over 550,000 people will die from cancer this year

  3. Fifteen Leading Causes of Death, US, 2004 Percent (%) of Total Deaths Rank Cause of Death Number of Deaths Death Rate* *Rates are per 100,000 population and age-adjusted to the 2000 US standard population. Source: US Mortality Public Use Data Tape, 2004, National Center for Health Statistics, Centers for Disease Control and Prevention, 2006.

  4. What is cancer? • Cancer is a collective name that refers to a group of many diseases with one common characteristic: uncontrolled cell growth or loss of the cell's ability to perform apoptosis (cell suicide). • Mutations occur to genes that control the normal process of cell growth and death • Gradual increase in the number of uncontrolled dividing cells • Mass of tissue occurs called a “tumor” (also called a neoplasm)

  5. Development of Cancer from genetically altered cell to metastasis

  6. Why do mutations happen? Some cancer-causing mutations are simply spontaneous errors that appear in normal DNA molecules when cells duplicate their DNA prior to cell division Some are related to environmental factors/exposures, diet, lifestyle choices or heredity (a few “suseptibility genes” passed down)

  7. Accumulation of mutations in these 3 areas=cancer • The mutations that contribute to the development of cancer affect three general classes of gene: • Oncogenes • Tumor suppressor genes • DNA repair genes

  8. Cancer Tends to Involve Multiple Mutations • The formation of cancer usually requires multiple mutations, with the chance increasing for mutations to accumulate and cancer to develop with more years of life (Doll & Peto, 1981).

  9. Heredity and Cancer • Cancer is not considered an inherited illness since 80 to 90 percent occur in people with no family history of the disease • E.g., only about 5 percent of breast cancers are thought to be due to inheritance of particular form(s) of a "breast cancer susceptibility gene."

  10. Different Kinds of Cancer • Carcinomas • Most common types of cancer • Arise from the cells that cover external and internal body surfaces Lung, breast, prostate, and colon are the most frequent cancers of this type in the United States • Sarcomas • Arise from cells found in the supporting tissues of the body such as bone, cartilage, fat, connective tissue, and muscle • Lymphomas • Arise in the lymph nodes and tissues of the body's immune system • Leukemias • Cancers of the immature blood cells that grow in the bone marrow and tend to accumulate in large numbers in the bloodstream

  11. Tumor Grading/Staging • Microscopic examination also provides information regarding the likely behavior of a tumor and its responsiveness to treatment. • A low number grade (grade I or II) refers to cancers with fewer cell abnormalities than those with higher numbers (grade III, IV).

  12. Tumor Grading/Staging • Based on the answers to the following questions, the cancer is assigned a "stage." • 1. How large is the tumor, and how far has it invaded into surrounding tissues? • 2. Have cancer cells spread to regional lymph nodes? • 3. Has the cancer spread (metastasized) to other regions of the body?

  13. Why Cancer Is Potentially Dangerous • A malignant tumor, a "cancer," is a more serious health problem than a benign tumor because cancer cells can spread to distant parts of the body.

  14. Cancer Detection and Diagnosis • Early detection affects the outcome of the cancer • When cancer is found (type and how fast it is growing) • Invasion • Metastasized

  15. Early Cancer May Not Have AnySymptoms • Screening methods are designed to check for cancer in people with no symptoms. Some examples of screening methods are: • Pap Test/smear • Mammograms • Blood Tests (PSA) • Fecal Occult Blood Test (FOBT)

  16. Diagnose the presence of cancer • Screening tests indicate the possible existence of cancer, a doctor must then perform a biopsy • For leukemias, a small blood sample serves the same purpose • Microscopic examination will tell the doctor whether a tumor is actually present and, if so, whether it is malignant (i.e., cancer) or benign.

  17. Tumor grade and stage are related to cancer survival

  18. What Causes Cancer?

  19. Heredity? Behaviors? Other Factors? • In theory, differences in heredity or environmental risk factors might be responsible for the different cancer rates observed in different countries.

  20. Tobacco Use and Cancer • Cigarette smoking linked with cancer of the: • lung • Mouth • Larynx • Esophagus • Stomach • Pancreas • Kidney • Bladder • Cervix • Current estimates suggest that smoking cigarettes is responsible for at least one out of every three cancer deaths.

  21. Smoking-Related CancersRelative Risks Ex-smoker Current Smoker • Lip & Oropharangyeal 1.76 4.55 • Oesophageal 1.79 4.01 • Stomach 1.11 1.41 • Anal 1.83 3.18 • Pancreatic 1.15 3.18 • Laryngeal 2.86 7.48 • Lung 6.75 M 13.0 M • 5.07 W 11.4 F • Cervix 1.31 1.75 • Vulvar 1.37 3.42 • Penile 1.6 1.8 • Bladder 1.7 2.7 • Renal Parenchymal 1.61 1.64 • Renal Pelvic 1.95 3.96 Source: Single et al., Am J Public Health 1999;89:385-390.

  22. Low-Strength Radiation Some atoms give off radiation, which is energy that travels through space. Prolonged or repeated exposure to certain types of radiation can cause cancer.

  23. High-Strength Radiation • X-rays or radiation emitted from unstable atoms called radioisotopes • Stronger than ultraviolet radiation • Can penetrate through clothing and skin and into the body • High-strength radiation can cause cancers of internal body tissues

  24. Examples of Human Cancer Viruses

  25. Viruses • A few viruses also can trigger the development of cancer • Cannot reproduce on their own • Viruses are small infectious agents • Enter into living cells and cause the infected cell to produce more copies of the virus • Causes the cell to become malignant

  26. Bacteria and Stomach Cancer • The bacterium H. pylori, which can cause stomach ulcers, has been associated with the development of stomach cancer

  27. Breast cancer risk factors • Most common cancer in women and second to lung cancer in the number of cancer deaths among women • Causes/risk factors • Heredity • Long-term exposure to high blood levels of estrogen • Early onset of menstruation • Late onset of menopause • No children or first child after age 30 • Obesity • Current use of HRT • Alcohol use • Inactivity • Diet low in vegetables and fiber

  28. Prostate CancerRisk Factors • Age • Race (African American=higher) • Diet: high in calories • Male Hormones • Environmental Exposures • A Vasectomy, BPH, STD’s • Family History of Prostate Cancer

  29. Cancer Risk and Aging

  30. Summary of What Causes CancerSource: CDC Sexual Factors Alcohol Overuse Environmental & Occupational Factors Tobacco Use Other Factors Diet & Physical Activity

  31. Ways to prevent cancer: • Maintain a healthy weight; • Eat no more than two or three servings of red meat per week; • Take a multivitamin with folate every day; • Drink less than one alcoholic drink a day; • Eat five or more servings of fruits and vegetables per day; • Eat more high fiber foods such as whole grains, wheat cereals, bread, and pasta; • Include cruciferous vegetables in your diet (such as broccoli, cabbage, etc.); • Do not smoke; • Protect yourself from the sun; • Avoid certain workplace exposures; • Protect yourself and your partner(s) from sexually transmitted infections; and • Exercise regularly.

  32. Quick Quiz 3pts/ques 1. What is the most common cancer for men, women? 2. Give 3 risk factors for the most prevalent male cancer 3. Give 3 risk factors for the most prevalent female cancer 4. What is the common characteristic that makes cells result in cancerous growth?

  33. Quick Quiz cont. 5. What are the four main categories/kinds of cancer and describe what type of tissue that each arises from. 6. Compare benign vs malignant 7.Using no more than 5 sentences, describe how a genetically altered cell becomes cancer that has spread throughout the body 8. Describe the I-IV grading/staging system for cancer

  34. Quick Quiz, cont 9. How and to what extent does genetics play in the development of cancer? 10. List 3 ways cancers can be prevented

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