Stilboestrol (diethylstilbestrol) and the risk of ovarian cancer.

A follow-up survey of 908 women who had received 'Premarin' (conjugated equine oestrogen) for menopausal symptoms revealed 8 cases of ovarian cancer. This risk was 2 to 3 times greater than expected. The risk increased with the strength of premarin tablet usually taken, but not with the duration of use or total dose ingested. The excess risk of ovarian cancer in this group occurred primarily among 21 women who had also used stilboestrol (diethylstilbestrol). The results of this small trial are consistent with the increasing incidence of ovarian cancer in post-menopausal women in the U.S.A., and with the occurrence of stilboestrol-induced ovarian neoplasms in dogs.