COMMENTARY

More Good News About Oral Contraceptives

JoAnn E. Manson, MD, DrPH

Disclosures

August 14, 2015

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Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women's Hospital. I'd like to talk about an interesting study[1] that was recently published in Lancet Oncology on oral contraceptives and long-term reduction of the risk for endometrial cancer. The study projected that about 400,000 cases of endometrial cancer have been prevented in developed countries by the use of oral contraceptives (OCs) during the past 50 years, and that about 200,000 of these cases were in the past 10 years.

This was a meta-analysis of 36 epidemiologic studies that included more than 27,000 women with endometrial cancer and more than 100,000 controls. The study found that after 5 years of using OCs, there was about a 24% reduction in the risk for endometrial cancer. The reductions persisted for at least 30 years after stopping OCs and applied to both the high-dose OCs used in the 1960s and the lower-dose pills that have been used in recent decades. With 10-15 years of OC use, there was about a 50% reduction in the risk for endometrial cancer.

It has been known for a long time that there are both contraceptive and noncontraceptive benefits from the birth control pill. In terms of contraception, the pill has certainly provided control for women over reproductive family planning decisions. However, it is also useful for other indications, such as controlling irregular heavy menses, ovarian cysts, acne, and premenstrual-type symptoms.

Some risks need to be taken into account. During current use, there is an increased risk for venous thrombosis, myocardial infarction, and stroke, but the absolute risks tend to be quite small, especially in younger, healthy women. The risks can be higher in older women, women who smoke, or those who have hypertension or other vascular risk factors, but these cardiovascular risks tend to be limited to current use of OCs and don't persist after stopping.

We are now learning that there are many potential benefits of OCs that become apparent many years after stopping the pill, including the recent findings on endometrial cancer. It has also been known for a while that OCs can lower the risk for ovarian cancer in a similar manner. Ten to 15 years of use is associated with close to half the risk for ovarian cancer that persists many decades after use. There may also be a reduction in colorectal cancer, which has been suggested by several studies.

What are the implications of this report? Certainly, for a woman who is young, healthy, and using OCs for reproductive decisions and family planning, it would suggest that the benefits of OCs are very likely to counterbalance, if not outweigh, the risks. It also raises the possibility that in a small, select subgroup of women who are at increased risk for ovarian or endometrial cancer, such as women with BRCA1 or BRCA2 positivity or women with Lynch syndrome, there may be a role for chemotherapy prevention with OCs. However, this needs further study to really understand the balance of benefits and risks.

Thanks so much for your attention. This is JoAnn Manson.

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