Oral Contraceptives and Cancer: New Data

Andrew M. Kaunitz, MD


January 27, 2021

This transcript has been edited for clarity.

Hello. I'm Andrew Kaunitz, professor and associate chair in the ob/gyn department at the University of Florida, College of Medicine in Jacksonville.

Today I'd like to discuss good news from Britain regarding the use of oral contraceptives (OCs) and cancer risk. Many of those viewing this video see patients who seek our advice regarding contraception, and a common concern is that hormonal birth control increases cancer risk.

A new study based on data from the United Kingdom clarifies how the use of OCs affects the risk for cancer. Investigators used the UK Biobank, which includes hundreds of thousands of individuals recruited between 2006 and 2010, as well as national databases, to assess associations between OC use and risk for breast, ovarian, and endometrial cancer in women born between 1939 and 1970.

Among more than a quarter-million women, more than three quarters had used or were currently using the pill. Overall, the use of OCs was associated with an approximately 30% reduced risk for ovarian and endometrial cancer. In contrast, the risk for breast cancer was similar among those who have used OCs and those who had never used them.

Among women followed to age 55, results were similar for ovarian and endometrial cancers. However, among the same group, OC use was associated with a 10% higher risk for breast cancer.

With 20 or more years of OC use, risk reduction became even more robust for ovarian and endometrial cancer—40% and greater than 60%, respectively. Among long-term users, the risk for breast cancer was similar to that of never-users.

These findings clarify that the controversy over the association of breast cancer and OCs use may reflect different study methodologies, particularly with respect to timing. The authors suggest that although the lifetime risk for breast cancer may not differ between ever-users and never-users, there appears to be a transient small elevated risk associated with OC use.

Fears that taking the pill can increase the risk for breast cancer have prevented many women from using this convenient form of birth control. This study provides reassurance regarding the overall safety of oral contraception with respect to cancer. At the same time, it reinforces that, when used long-term, as the authors state, the pill "dramatically" reduces the risk for ovarian and endometrial cancer, and this protection persists for decades.

These findings will be useful in informing how we counsel patients regarding the benefits and risks of oral contraceptives.

Thank you for the honor of your time. I am Andrew Kaunitz.

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