Oral Contraceptive Use Lowers Ovarian Cancer Risk in BRCA1/2 Carriers

The use of oral contraceptives reduced the risk of ovarian cancer among women with the BRCA1/2 mutations at a similar rate as that seen among the general population, according to the results of a meta-analysis examining oral contraceptives as a chemoprevention strategy for these high-risk women.

However, according to researcher Patricia G. Moorman, PhD, MSPH, of Duke Cancer Institute, and colleagues, there currently is not enough evidence to recommended oral contraceptives as a chemoprevention strategy against ovarian cancer in women with BRCA1/2 mutations and, inversely, there is no evidence of increased risk of cancer to recommend against their use as a contraceptive.

Women who carry BRCA1/2 mutations have significantly increased risk of developing ovarian cancer. As such, researchers are trying to identify factors that may affect the likelihood of development of the disease in order to create primary prevention strategies. Among the possible prevention strategies is the use of oral contraceptives.

“Ever use of oral contraceptives is associated with an approximate 30% reduction in ovarian cancer incidence in the general population, with greater risk reductions with longer duration of use,” the researchers wrote. “If oral contraceptives reduce ovarian cancer incidence similarly in high-risk women, these drugs could be a viable prevention strategy for women who have not completed childbearing or who wish to avoid surgery.”

Moorman and colleagues conducted a meta-analysis of studies that looked at associations between oral contraceptive use and breast and ovarian cancer in women with BRCA1/2 mutations or family history of breast or ovarian cancer. Their search identified 6,476 citations, which they narrowed to 6 studies of ovarian cancer and 8 studies of breast cancer in mutation carriers.

Based on these data, the researchers found an inverse association between oral contraceptives and ovarian cancer among BRCA1/2 mutation carriers (OR=0.58; 95% CI, 0.46 to 0.73).

“The inverse association we observed with ever use of oral contraceptives for the combined group of BRCA1/2 mutation carriers (OR= 0.58) was stronger than what we observed in our meta-analysis in the general population (OR=0.73) and what has been reported in an earlier pooled analysis,” the researchers wrote. “Analyses restricted to BRCA1 and BRCA2 carriers found similar ORs for oral contraceptive use within each gene group, and a test for differences between groups was not statistically significant.”

A nonsignificant association between oral contraceptives and increased risk of breast cancer was also found (OR=1.21; 95% CI, 0.93-1.58).

The researchers did not have sufficient data to perform an analysis looking at duration or timing of oral contraceptive use and its effect on ovarian and breast cancer risk.

Pertinent Points:
- Ever use of oral contraceptives’ association with breast and ovarian cancers is similar among BRCA1/2 mutation carriers and the general population.
- Data are currently insufficient to recommend oral contraceptives as a chemoprevention strategy among women with BRCA1/2 mutations. 

References:

Moorman PG, Havrilesky LJ, Gierisch JM, et al. Oral contraceptives and risk of ovarian cancer and breast cancer among high-risk women: a systematic review and meta-analysis. J Clin Oncol. 2013;doi:10.1200/JCO.2013.48.9021.