Oral Contraceptives May Protect Against Some Cancers for 30 Years

Use of oral contraception may protect against certain cancers for many years after discontinuing use, according to the results of a recent study.

Despite previous research and the extensive use of oral contraceptives, questions remain about the safety and very long-term cancer risk associated with their use.

In order to explore the very long-term cancer risks or benefits associated with the use of combined oral contraceptives, researchers  recruited 46,022 women to the UK Royal College of General Practitioners’ Oral Contraception Study in 1968 and 1969. The women were observed for up to 44 years.
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Overall, there were 4661 ever users of combined oral contraceptives with at least 1 cancer and 2341 never users with at least one cancer during 884,895 woman-years and 388,505 woman-years of observation, respectively.

Ever use of oral contraceptives was associated with reduced colorectal, endometrial, ovarian, and lymphatic and hematopoietic cancer risk. Ever users who smoked at recruitment had an increased risk of lung cancer. An increased risk of breast and cervical cancer seen among current and recent users appeared to be lost after approximately 5 years following cessation of oral contraception use.

“There was no evidence of new cancer risks appearing later in life among women who had used oral contraceptives. Thus, the overall balance of cancer risk among past users of oral contraceptives was neutral with the increased risks counterbalanced by the endometrial, ovarian, and colorectal cancer benefits that persist at least 30 years,” the researchers concluded.

—Michael Potts

Reference:

Iversen L, Sivasubramaniam S, Lee AJ, Fielding S, Hannaford PC. Lifetime cancer risk and combined oral contraceptives: the Royal College of General Practitioners’ Oral Contraception Study [published online February 8, 2017]. AJOG. doi: dx.doi.org/10.1016/j.ajog.2017.02.002