[An epidemiological study on the relationship between oral contraceptives and benign breast disease].

The relationship of benign breast disease (BBD) and oral contraceptive (OC) use was analyzed in a case-control study conducted in Milan on 288 women with clinically relevant and histologically confirmed BBD (cases) and 285 age matched controls with a spectrum of acute conditions apparently unrelated to OC use. Compared to women who had never used OCs, the relative risk (RR) for users was 1.0 (95% confidence interval: 0.6-1.5). Likewise, there was no siginficant association with duration of use; however, a significantly lower relative risk emerged in women taking OCs during the year before breast biopsy (RR=0.4; 95% confidence interval: 0.2-0.8). The protection in current users increased with increasing duration of use. In spite of this finding, the overall results of the study do not support the hypothesis that OC use protects against development of histologically confirmed and clinically relevant benign breast disease.