Cancer

1. Cancer Chapter 16

2. Figure 16.1 Percentage of all cancer deaths linked to risk factors

3. 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 purpose • Benign tumor: Mass of cells enclosed in a membrane that prevents their penetration of other tissues • Malignant tumor: Mass of cells that 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.

4. Metastasis • Definition: The spread of cancer cells from one part of the body to another • Primary tumor: original location of cancer • Secondary tumors: New tumors

5. Figure 16.2 Tumor development occurs in stages

6. Cancer stages Staging is based on size

7. Types of cancer • Classified according to types of cells that give rise to them • Carcinomas – arise from epithelial tissue • Ex., skin • Sarcomas – arise from connective tissue • Bone, cartilage, etc. • Lymphomas- arise from lymph nodes • Leukemias - Cancer of the blood-forming cells in bone marrow.

8. 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 be prevented by avoiding exposure to tobacco smoke • Regular screening and self-examinations could save an additional 100,000 lives per year.

9. Lung cancer • Leading cause of cancer deaths in the U.S. • ~158,000 deaths/year • Risk factors • Tobacco smoke (including ETS) contributes to 90% of lung cancer deaths • Detection • Symptoms: Persistent cough, chest pain, or recurring bronchitis • Difficult to detect early and symptoms usually do not appear until the invasive stage • Diagnosis: CT scan, chest x-ray or sputum examination, bronchoscopy

10. Lung cancer • Treatment • If caught early, localized cancers can be treated with surgery • A combination of radiation and/or chemotherapy can be used in addition to surgery

11. Colon and rectum (colorectal) 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

12. Colon and rectum (colorectal) cancer • Detection and treatment • Symptoms: bleeding from rectum and changes in bowel habits • Regular screening tests are recommended beginning at age 50 • Treatment • Primarily Surgery • Radiation and chemotherapy can be used

13. Breast cancer • Most common cancer in women • Causes almost as many deaths in women as lung cancer • Risk factors • Strong genetic factor: inheriting mutated BRCA1/2 genes • Age: Most common in women over 50 • Early onset of menstruation • First child after 30 • Current use of HT • Unhealthy diet and lifestyle

14. Breast cancer • Detection • Symptoms may include a lump, changes in size, dimpled, redness or a scaly of nipple or breasts • ACS recommends 1 mammogram/year (women over 40) • Clinical and Self breast exams (starting at age 20)

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16. Breast cancer • Treatment • A cure is most likely if detected early • Removal of the tumor if discovered before it has spread.

17. Prostate cancer • Most common cancer in men • Risk factors • Age (more than 60% of cases diagnosed in men over 65) • Genetic predisposition • Diet and Lifestyle • African American and Jamaican men have highest rates in the world

18. Prostate cancer • Detection • Symptoms may include changes in urinary frequency, weak or interrupted urine flow, painful urination, blood in urine • Blood test: Prostate-specific antigen (PSA) • Rectal exam

19. Prostate cancer • Treatment • Surgical removal of the prostate and radiation (depends on stage and age) • Radioactive seeds

20. Cancers of the female reproductive tract • Cervical cancer • Most cases stem from human papillomavirus (HPV) infection (STD) • Prevention • The PAP test is a highly effective screening test for this cancer • All sexually active women ages 18-65 should be tested regularly • A vaccine against HPV is Gardasil

21. Skin cancer • Main types of skin cancer • Basal cell carcinomas • Squamous cell carcinomas • Melanoma (most deadly type) • Most common form of cancer • 1 million cases per year (68,000 are melanoma) • Risk factors • Excessive exposure to UV rays • Pale skin, easily sunburned • Caucasians are 10X more likely than African Americans to develop basal and squamous cell carcinoma

22. Skin cancer • Prevention • Avoid long term overexposure to sunlight • Detection of Melanoma • ABCD screen test

23. Causes of cancer • The role of DNA mutations and Cancer • Mutagens: substances that cause mutations like radiation, certain viruses, ingested chemicals, environmental pollution • 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 • If a hereditary cancer, abnormal gene is present in sperm/egg • If not hereditary, a mutation has occurred • Tobacco Use • Dietary Factors -fried foods, low fiber, lack of phytochemicals from fruits and vegetables. • Inactivity and Obesity

24. Causes of cancer • Cancer promoters • Cancer promoters do not directly produce mutations, instead they accelerate the growth of cells without damaging or permanently altering the DNA • Estrogen is an example

25. Figure 16.8 The seven major warning signs of cancer

26. Preventing Cancer • Lifestyle choices • Avoid tobacco • Control diet and weight • Regular exercise • Protect skin from the sun • Avoiding environmental and occupational carcinogens • Follow recommendations for cancer screenings 26