Oral Contraceptive Use and Increases in Breast, Ovarian, and Endometrial Cancers

To the Editor Michels and colleagues claim that long past oral contraceptive (OC) use reduces the risk of ovarian and endometrial cancer. Carcinogenic effects of more recent exposures to menopausal progestin and/or estrogen hormone therapy (HT) are ignored. Among the entire sample of women aged 50 to 71 years (median age, 60 years), 118 144 (60%) formed a control reference group that included both never users and women who had taken OCs for less than 1 year. Only 10% of women took OCs for at least 10 years. A follow-up 11 years later found that 18 199 women had cancer: 61% breast cancer, 19% colorectal cancer, 13% endometrial cancer, and 7% ovarian cancer.

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