LWBK1006-12 LWW-Govindan-Review November 24, 2011 11:21
Chapter 12•Cancer Prevention 139Answer 12.7. The answer is A.
In smokers, the Alpha-Tocopherol, Beta-Carotene Trial (ATBC) and the
Carotene and Retinol Efficacy Trial (CARET) showed increased risk of
lung cancer in patients receiving beta-carotene with or without retinol.
Although topical all-trans retinoic acid (ATRA) might cause regression of
cervical dysplasia, this effect was not seen in studies involving systemic
retinoids or beta-carotene. Prospective studies found no protective effect
of beta-carotene supplementation. Retinoids and beta-carotene have been
studied extensively in both clinical and epidemiologic trials. Systemic
retinoids were initially shown to reduce skin cancer incidence by 63%
during therapy in patients with xeroderma pigmentosum. However, the
protective effect was lost after discontinuing the treatment.Answer 12.8. The answer is D.
Several studies have shown protective effects from NSAIDs in patients
with colorectal cancer. Although regular use of aspirin was associated
with protective effects in population base studies, the benefit of low-dose
aspirin was not yet clear in randomized clinical trials. The limited benefit
of NSAIDS, including low-dose aspirin, in preventing colorectal cancer,
does not justify their use in average-risk individuals. Sulindac, at high
dose, was associated with both regression of existing polyps and preven-
tion of new polyps in patients with FAP, but the protection was transient
and incomplete. Although the cyclooxygenase-2 inhibitors rofecoxib and
celecoxib were shown to reduce the risks of metachronous adenoma, the
studies were terminated early because of their side effects, being unable
to detect the reduction of colorectal cancer incidence. Although NSAIDs
reduce the risk of colorectal adenoma and colorectal cancer, these agents
are associated with significant gastrointestinal and cardiovascular toxi-
cities, which outweigh the benefits. Therefore, the best strategy for the
general population remains effective screening.Answer 12.9. The answer is C.
Raloxifene is a nonsteroidal selective estrogen receptor modulator that
binds to estrogen receptor leading to estrogen agonist effects in some
tissues and estrogen antagonist effects in others. Raloxifene has estrogen
agonist activity in the bone but is less active than tamoxifen in the uterus.
Unlike tamoxifen, raloxifene was not associated with increased risk of
uterine cancer. Because of raloxifene’s agonist activity in bone, it reduced
the risk of vertebral fracture. Raloxifene does not increase the risk of
coronary artery heart disease, but studies showed increased risk of venous
thromboembolism and fatal stroke.Answer 12.10. The answer is C.
The lifetime risk of ovarian cancer increases from a baseline of 1.5% to
about 15% to 25% inBRCA2carriers. AlthoughBRCAmutations are
rare in most populations, they occur in approximately 1 in 40 Ashke-
nazi Jews. The median age for sporadic epithelial ovarian cancer is 60
years. Among patients with hereditary ovarian cancer,BRCA1 mutation