Certain Birth Control Associated With Decreased Risk of Ovarian Cancer

New research indicates a link between contemporary combined hormonal contraceptives and a reduction in ovarian cancer risk in women of reproductive age. 

The prospective, nationwide study was conducted in Denmark between 1995 and 2014 and included women aged between 15 and 49 years during that time (n = 1,879,227). Women who immigrated after 1995, had cancer (except non-melanoma skin cancer), had venous thrombosis, or received infertility treatment prior to the start of the study were not included. Eligible women were divided into three categories: never users (no record of being dispensed hormonal contraception), current or recent users (≤ 1 year after stopping use), or former users (> 1 year after stopping use) of different hormonal contraceptives. Women in the current or recent use and former use of any hormonal contraception were at a significantly lower risk of ovarian cancer than the never users (relative risk 0.58 [95% confidence interval 0.49 to 0.68] and 0.77 [0.66 to 0.91], respectively). 

“The reduced risk seems to persist after stopping use, although it is not yet known how long for,” the researchers wrote. 

The longer women reported currently or previously using hormonal contraception, the more their risk decreased (from 0.82 [0.59 to 1.12] with ≤ 1 year use to 0.26 [0.16 to 0.43] with > 10 years’ use; P < 0.001 for trend). Progestogen-only products had no association with ovarian cancer risks. The researchers estimated that using hormonal contraception prevented 21% of ovarian cancers in the study population.

The findings were published in The BMJ 

The study authors could not definitively say why hormonal contraception use reduced the risk of ovarian cancer, but they believe the benefits are long-term. 

“Combined hormonal contraceptives suppress ovulation so protection against neoplastic development is feasible, but the exact mechanisms by which hormonal contraceptives reduce ovarian cancer risk are unclear,” they wrote. “Whatever the biological mechanisms, the epidemiological evidence suggests a longlasting protection against most types of ovarian cancer from combined oral contraception.” 

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Source: The BMJ