Devita, Hellman, and Rosenberg's Cancer

LWBK1006-05 LWW-Govindan-Review November 24, 2011 11:20

74 DeVita, Hellman, and Rosenberg’s CANCER: Principles and Practice of Oncology Review

ANSWERS

Answer 5.1. The answer is C.

Prevalence reflects the public health burden of the disease (i.e., how many

patients need to be treated and/or followed by the health system), and

incidence is considered a more relevant measure of disease frequency for

etiologic evaluation. An example would be breast cancer in women and

prostate cancer in men are more prevalent, whereas lung cancer compro-

mises only a small fraction of the prevalent cases but is the most common

fatal cancer. The incidence of a disease can vary depending on the report-

ing to the cancer diagnosis and the presence of screening tests such as

prostate-specific antigen.

Answer 5.2. The answer is D.

The SEER database covers approximately 26% of the US population.

Answer 5.3. The answer is D.

Both molecular epidemiology and genetic epidemiology have an emphasis

on molecular analysis, but linkage analysis is usually performed in genetic

epidemiology studies because participants are genetically related family

members.

Answer 5.4. The answer is A.

Ecological studies use groups of people as the unit and are performed

when the level measures of exposure and/or outcome are available. An

example would be the relationship between dietary fat intake and the

incidence of a type of cancer by country.

Answer 5.5. The answer is D.

Tobacco smokers are more likely to carry matches than nonsmokers.

Therefore, the increased risk for lung cancer is due to tobacco smok-

ing and not from carrying matches. This is an example of confounding

where a third variable (which has not been taken into account in the

study) affects the association between the exposure and disease resulting

in an erroneous conclusion.

Answer 5.6. The answer is D.

Although this figure is popular and useful, it significantly overestimates

the risk in the never-smoking population and underestimates the risk on

the smoking population. The incidence of lung cancer also increases with

age, so this number overestimates the risk in younger people and under-

estimates the risk in older people.

Answer 5.7. The answer is D.

Age standardization eliminates differences in the age structure, which is

important because cancer has a higher incidence in older people, and a