Oral Contraceptives May Reduce Endometrial, Ovarian Cancer Risk Decades After Stopping Use

Oral contraceptive use was associated with a reduced risk of endometrial and ovarian cancer, which extended up to three decades after patients stopped its use.

However, data from the observational study published in Cancer Research demonstrated that there was not a similar link in terms of a reduced risk of breast cancer.

“It was clear that women who had used oral contraceptive pills had a much lower risk of developing both ovarian and endometrial cancer. Fifteen years after discontinuing with oral contraceptives, the risk was about 50% lower,” said study author Asa Johansson, of Uppsala University in Sweden, in a press release. “However, a decreased risk was still detected up to 30 to 35 years after discontinuation."

The study authors conducted an observational study that consisted of 256,661 women who were recruited into the UK Biobank (a separate study aimed at improving the prevention, diagnosis and treatment of various diseases in the United Kingdom) between 2006 and 2010. The women who were included in this observational study were born between 1939 and 1970, and self-reported on lifestyle, medical history, previous exposures and physical measurements.

The goal of the study, according to the authors, was to identify any long-term connections between the risk of breast, endometrial and ovarian cancer and oral contraceptive use and if risks differed among women who never used oral contraceptives.

Of the women included in the observational study, 82% (210,433 people) were considered ever users, meaning they had used or still were using oral contraceptives. The remaining 18% (46,218 people) never used oral contraceptives and were considered never users.

The authors identified 17,739 cases of breast cancer, 1,966 cases of ovarian cancer and 2,462 cases of endometrial cancer among the study participants. The number of cancer cases was significantly higher among those who never used oral contraceptives which was attributed to a higher median age, compared to those who used contraceptives.

The study results showed that the risk of developing ovarian or endometrial cancer was lower among ever users, compared to never users. Although, the authors did not see the same significant link between oral contraceptive use and reduced risk of breast cancer.

“Surprisingly we only found a small increased risk of breast cancer among oral contraceptive users, and the increased risk disappeared within a few years after discontinuation,” Johansson noted in the release. “Our results suggest that the lifetime risk of breast cancer might not differ between ever and never users even if there is an increased shore term risk.”

The authors also noted that the longer a patient used an oral contraceptive the lower risk, which was specifically seen in endometrial cancer. Compared to previous studies, the lengthy follow-up, according to the authors, demonstrates that oral contraceptive use reduces the risk of endometrial and ovarian cancer for up to 30 to35 years after discontinuation.

The results, according to the authors, emphasize the importance of better understanding the short- and long-term effects of exposure to these hormone medications.

“In addition to protecting against pregnancy, our results have shown that oral contraceptive pills also have other positive effects,” said study author Therese Johansson, a post doctorate student at Uppsala University, in the release. “Our results can enable women and physicians to make more informed decisions about which women should use oral contraceptive pills.”

However, the authors noted that it is important to consider that oral contraceptives have changed over the years. Today, most oral contraceptives include lower doses of estrogen and progestogen, compared to those that the women in this study used.

“Our results may therefore not directly be applicable to the oral contraceptives that are commonly used today but should be important for future drug development of cancer prevention and of new cancer types,” the authors concluded.

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