Women who have had breast cancer appear to face little risk of a cancer in the other breast due to oral contraceptive or postmenopausal hormone therapy use, according to research published in the March 20 issue of the Journal of Clinical Oncology.
Jane C. Figueiredo, of the University of Southern California in Los Angeles, and colleagues analyzed data from 708 women with a history of asynchronous bilateral breast cancer (who represented cases) and 1,395 control women with unilateral breast cancer. The researchers collected information on women's medical history, hormone use, and other factors.
OC use before or after first breast cancer diagnosis wasn't significantly associated with asynchronous bilateral breast cancer risk, nor was postmenopausal hormone use before or after breast cancer diagnosis significantly associated with increased risk. The investigators found that duration of use of either type was also not associated with risk.
"These findings have important clinical implications for women with breast cancer. Although current clinical guidelines do not recommend that women with a history of breast cancer use oral contraceptives or postmenopausal hormones, results from this large observational study, combined with those from other observational studies and from clinical trials, suggest that use of these exogenous hormone preparations does not increase the risk of second breast primaries."
Figueiredo JC, Bernstein L, Capanu M, et al. Oral contraceptives, postmenopausal hormones, and risk of asynchronous bilateral breast cancer: the WECARE Study Group. J Clin Oncol. 2008;26:1411-1418.