Onc 5 - Cancer Prevention And Host Defense

Question 1

What are the five most important lifestyle factors that impact cancer risk?

Answer 1

Smoking. Obesity. Poor diet. Inactivity. Sun exposure.

Question 2

What is the number 1 cause of preventable cancer?

Answer 2

Smoking.

Question 3

Why does Obesity encourage cancer growth?

Answer 3

Because obesity causes increased levels of insulin and insulin-like growth factor (IGF-1). IGF-1 stimulates growth and inhibits apoptosis.

Question 4

What two cancers have been associated with physical inactivity?

Answer 4

Colon cancer. Breast cancer.

Question 5

What is the USPSTF recommended Screening for Breast cancer?

Answer 5

Breast self-exam: not recommended. Clinical breast exam: Insufficient evidence. Mammograms (reduce mortality in women over 50 y.o: 50-74 y.o mammograms every 2 years. +75: insufficient evidence.

Question 6

What is the USPSTF recommended Screening for Cervical cancer.

Answer 6

Pap smear: start at age 21 and do it every 3 years and stop at age 65.

Question 7

What is the USPSTF recommended Screening for Prostate cancer?

Answer 7

Digital rectal exam: No recommendation for or against. PSA: Insufficient evidence for men below 75, do not do it for men above 75.

Question 8

What is the USPSTF recommended Screening for Colon cancer?

Answer 8

Colonoscopy every 10 yrs beginning at age 50: remove all the polyps. If they refuse colonoscopy or can’t be done, do flexible sigmoidoscopy every 5 yrs beginning at age 50. Or do annual fecal occult blood test, Cannot recommend for or against colon cancer screening for patients above the age of 75. Do not screen above 85. If family history of colon cancer, start screening at age 40 or 10 yrs younger than age at which family member was diagnosed. Insufficient evidence to recommend for or against CT colonography.

Question 9

What immune cells are involved in killing cancer cells?

Answer 9

CD8+ cytotoxic lymphocytes. Natural killer (NK) cells. Macrophages.

Question 10

What type of antigens can the immune system use to distinguish tumor cells from healthy cells?

Answer 10

Products of mature genes (ex: RAS oncogenes, BCR-ABL proteins). Over-expressed normal cellular proteins (ex: tyrosinase products in melanoma). Tumor antigens produced by oncogenic viruses (e: HPV, EBV). Oncofetal antigens (ex: alphaFP, CEA). Altered surface glycoproteins and glycolipids (ex:CA-125, CA19-9). Cell type-specific differentiation antigen (ex:CD20).

Question 11

What mechanisms do cancer cells use to evade the immune system?

Answer 11

Selective outgrowth of antigen-negative variants. Reduced expression of MHC molecules. Lack of co-stimulation. Immunosuppression (TGF-beta). Antigen masking (mucupolysaccharides, glycocalyx). Apoptosis of the cytotoxic T cells (FasL).

Question 12

What is currently the most effective intervention in the screening and prevention of Lung cancer?

Answer 12

Stop smoking.

Question 13

What is currently the most effective intervention in the screening and prevention of Cervical cancer?

Answer 13

Pap smears, HPV vaccine.

Question 14

What is currently the most effective intervention in the screening and prevention of Renal cell carcinoma?

Answer 14

Stop smoking.

Question 15

What is currently the most effective intervention in the screening and prevention of Breast cancer?

Answer 15

Screening mammograms.

Question 16

What is currently the most effective intervention in the screening and prevention of colon cancer?

Answer 16

Colonoscopy.

Question 17

Which male patients should be screened for prostate cancer w/ a serum PSA?

Answer 17

Discuss prostate cancer screening w/ men ages 50-75.

Question 18

What is the primary immune system cell type involved in host tumor immune surveillance?

Answer 18

Cytotoxic T cells.

Question 19

How can tumor cells evade attack from cytotoxic T cells?

Answer 19

Not expressing MHC class I.

Question 20

How might tumor cells induce apoptosis of T cells that would antagonize them?

Answer 20

Expressing FasL on the surface of the tumor cell.