Abstract

PIP: A review of data pooled from 54 case-control studies concluded that both current users of oral contraceptives (OCs) and recent discontinuers have a slightly elevated risk of breast cancer (odds ratios, 1.24 for current users and 1.16 for women who discontinued OC use 1-4 years earlier). It should be noted, however, that the pooling of data involved in this analysis cannot overcome methodological problems inherent in the individual studies, particularly selection bias. The risk of breast cancer in the fertile, sexually active women who use OCs may differ from that in sexually inactive or infertile nonusers. Moreover, women who consider themselves to be at personal risk of breast cancer may opt not to use the pill. The relationship of sensitivity to exogenous hormones, which leads many women to discontinue OC use, to hormone production and breast cancer risk is unknown. Other factors that may have an impact on breast cancer risk include age at starting and stopping OC use, continuity and duration of use, and reproductive history variables such as pregnancies, childbearing, and breast feeding. For example, both OC use before 20 years of age and long-term use before first pregnancy are increasingly common. The impact of current OC use patterns on breast cancer risk should be the focus of future methodologically sound case-control studies.