5 Cancer Screening

Megan E. Wren

QUESTIONS

Each of the numbered items below is followed by lettered answers. Select the ONE lettered answer that is BEST in each case unless instructed otherwise.

Question 5.1 Studies of screening for cancer are subject to several types of bias. If screening detects a cancer earlier (before it becomes symptomatic), but treatment has no effect on the course of the disease, then the subject will seem to live longer than if he/she had presented symptomatically (i.e., the cancer is known for a longer period of time, but the time of death is not altered). This type of bias is known as

A. Lead-time bias.

B. Length bias.

C. Selection bias.

D. Overdiagnosis bias.

Question 5.2 In planning a prostate cancer screening program you are concerned that a prostate specific antigen (PSA) threshold of 4 ng/mL has a sensitivity of just 24% for the diagnosis of prostate cancer. You can anticipate that lowering the PSA threshold to 2.5 ng/mL threshold will

A. Decrease the positive predictive value (PPV).

B. Decrease the rate of true-positive results.

C. Decrease the sensitivity.

D. Increase the positive predictive value (PPV).

E. Increase the specificity.

Question 5.3 In the PLCO Cancer Screening Trial men were randomized to receive annual PSA testing for 6 years or usual care. At the conclusion of the 13 year follow-up period it was found that there was a high rate of PSA testing among men randomized to the control arm. This “drop-in” had what effect on the results?

A. Increased the positive predictive value (PPV) of the PSA test.

B. Increased the relative risk reduction (RRR) of the screening arm as compared with the control arm.

C. Reduced the sensitivity of the PSA test.

D. Reduced the statistical power of the study to detect differences in outcome between the two arms.

Question 5.4 The U.S. Preventive Services Task Force (USPSTF)

A. Is composed of government employees with limited clinical experience.

B. Formulates recommendations based on expert opinion more than on evidence based medicine.

C. Weighs benefits and harms of screening tests in the context of cost effectiveness.

D. Weighs benefits and harms of screening tests without considering cost effectiveness.

Question 5.5 A new screening test for ovarian cancer was developed. It was tested in a tertiary care academic medical center in a group of women with breast cancer (BRCA) mutations and was found to have a sensitivity of 70%, specificity of 90%, and positive predictive value (PPV) of 10%. If a woman in the study population is found to have a positive (abnormal) test result, how would you interpret it?

A. There is a 30% chance that this represents a false-positive result.

B. There is a 10% chance that this represents a false-positive result.

C. There is a 9 in 10 chance that this represents a false-positive result.

D. You can be 90% sure that your patient has the disease.

Question 5.6 If the use of this test (from Question 5.5) is expanded to the general population, it is expected that

A. The test sensitivity will be lower.

B. The test specificity will be lower.

C. The PPV will be lower.

D. The test specificity will be higher.

Question 5.7 In analyzing a randomized controlled trial of a screening test which is the best indicator of effectiveness?

A. Absolute reduction in mortality

B. Evidence of stage shift

C. Increased 5-year survival

D. Relative reduction in mortality

Question 5.8 Which statement regarding screening for breast cancer is TRUE?

A. The monthly breast self-examination (BSE) is a crucial component of breast cancer screening programs.

B. The BSE has been shown to be ineffective for breast cancer screening.

C. Increasing the interval of mammographic screening from 1 year to 2 years results in a halving of the mortality benefit.

D. Mammography has a higher positive predictive value (PPV) for women aged 40 to 49 as compared with women aged 50 to 59.

Question 5.9 The American Cancer Society (ACS) recommends annual screening mammography and MRI starting at age 30 for women at high risk for breast cancer including which of the following? (Select two correct responses)

A. Women with a history of fibrocystic breast disease

B. Women with a history of mantle radiation for Hodgkin disease

C. Women with a known BRCA mutation

D. Women with increased mammographic breast density

Question 5.10 A 19-year-old woman presents for a health maintenance visit. She has been sexually active for 4 years and has had one episode of chlamydia. What is the recommended approach to cervical cancer screening for her?

A. Begin annual screening with cervical cytology (Pap smear) plus HPV cotesting.

B. Begin annual screening with cervical cytology alone.

C. No cervical cancer screening at this time; start screening at age 21 with cervical cytology alone.

D. No cervical cancer screening at this time; start screening at age 21 with cervical cytology and HPV cotesting every 3 years.

Question 5.11 A 40-year-old woman had her first screening mammogram and was noted to have increased mammographic breast density. Current evidence suggests that the best recommendation for future breast cancer screening would be

A. Annual mammography alone.

B. Annual mammography + annual MRI.

C. Annual mammography + monthly breast self-examination (BSE).

D. Annual mammography + monthly breast self-examination (BSE) + annual MRI.

Question 5.12 The United States Preventive Services Task Force (USPSTF), the American College of Obstetricians and Gynecologists (ACOG), and the American College of Physicians (ACP) agree on which one of the following recommendations for ovarian cancer screening in women ages 20 to 65 years without oophorectomy?

A. Annual pelvic examination for all women

B. Annual serum CA-125 measurement

C. No population-based screening is recommended

D. Transvaginal ultrasound every 5 years

E. Two-stage screening: annual CA-125, then transvaginal ultrasound if elevated or rising CA-125

Question 5.13 A 44-year-old woman had a total hysterectomy for fibroids and menorrhagia. What is the recommended approach to cervical cancer screening for her?

A. Cervical cytology testing should be discontinued.

B. Cervical cytology testing should be performed annually indefinitely.

C. Cervical cytology testing should be performed every 1 to 3 years until age 65 years.

D. Cervical cytology testing plus HPV cotesting should be performed every 5 years until age 65 years.

Question 5.14 In the Mayo Lung Project randomized controlled trial more than 9,200 male smokers were randomized to intensive screening (sputum cytology and CXR every 4 months for 6 years) or a control group (same tests performed annually). After nearly 20 years of follow-up there were more lung cancers diagnosed in the intensive screening arm versus the control arm (585 vs. 500) but the intensive screening arm did not show improvement in lung-cancer mortality (4.4 lung cancer deaths per 1,000 person-years in the intensively screened arm vs. 3.9 per 1,000 person-years in the control arm). This is best explained by

A. Lead-time bias.

B. Overdiagnosis.

C. Selection bias.

D. Stage shift

Question 5.15 Based on the results of the National Lung Screening Trial (NLST) several organizations recommended consideration of lung cancer screening with low-dose computerized tomography (LDCT) for patients who would have qualified for the trial. Eligible patients had to have which two of the following criteria? (Select two correct responses)

A. Age less than 60 years

B. At least a 30 pack-year smoking history

C. At least a 50 pack-year smoking history

D. Current smoker

E. Relatively good health

Question 5.16 Which of the following statements regarding prostate cancer screening is TRUE?

A. Intensity of prostate cancer screening has been shown to correlate with the degree of mortality benefit.

B. Prostate cancer screening and therapy are associated with significant harms.

C. PSA levels are unaffected by benign prostate diseases.

D. Routine annual PSA testing is recommended for all men ages 55 to 74 years.

Question 5.17 A 50-year-old-man has no family history of colorectal cancer or polyps. He inquires about CT colonography (“virtual colonoscopy”) for screening as compared to traditional colonoscopy (endoscopy). Which one is TRUE?

A. CT colonography does not require a full bowel preparation

B. CT colonography requires sedation

C. CT colonography is only diagnostic; a colonoscopy would be required if any polyps need removal

D. CT colonography is only half a sensitive as colonoscopy

Question 5.18 More frequent screening for colorectal cancer (CRC) is recommended in certain high risk individuals. Which two of the following groups need to have screening increased to colonoscopy every 5 years starting by age 40? (Select two correct responses)

A. First-degree relative with CRC or adenomatous polyp at age ≥60 years

B. One first-degree relative with CRC or adenomatous polyps diagnosed at age <60 years

C. One second-degree relative with colorectal cancer

D. Two or more first-degree relatives with CRC

E. Two second-degree relatives with CRC

Question 5.19 Which of the following CRC screening tests can directly prevent colorectal cancer?

A. CT colonography (“virtual colonoscopy”)

B. Double-contrast barium enema

C. Fecal immunochemical testing (FIT)

D. High-sensitivity fecal occult blood testing (FOBT)

E. Optical colonoscopy (endoscopy)

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