Contraceptives Reduce the Risk of Uterine Cancer Later in Life

Endometrial (uterine) cancer currently ranks as the 10th deadliest cancer, killing nearly 8,000 women every year in the United States.  It's been known for some time that oral contraceptives reduce the risk of endometrial cancer.  But women tend to take oral contraceptives only for a short period of their life when they are relatively young, and endometrial cancer is not common in younger women.  Is there any protective effect of prior contraceptive use against the development of endometrial cancer later in life, when women are no longer using using oral contraceptives?

To find out, researchers combined the data from 36 previous studies comprising over 27,000 women who had developed endometrial cancer (cancer patients), and nearly 116,000 women who remained healthy (controls).  The median age of cancer diagnosis among the cancer patients was 63 years, generally well after contraceptive use had stopped.   Just over a third of the cancer patients had used oral contraceptives; the median length of use was just three years.

The results of the study showed a clear association between oral contraceptive use and the risk of endometrial cancer later in life.  Greater protection was associated with longer contraceptive use. Overall, women who had used oral contraceptives were 31% less likely to develop endometrial cancer than women who had never used oral contraceptives. The authors estimate that in developed countries, oral contraceptive use has prevented over 200,000 cases of endometrial cancer in just the past decade.

Of course the primary reason for using oral contraceptives is to prevent an unplanned pregnancy.   A long-term reduced risk of endometrial cancer appears to be a very real secondary benefit, however. Although one might suspect that other hormonal methods of birth control such as hormonal implants might also reduce the risk of endometrial cancer, that has not yet been determined.