Endometriosis may quadruple risk of ovarian cancer, study finds

Women with endometriosis may have a substantially increased risk of ovarian cancer, new research suggests.

In the study, women with endometriosis were more than four times as likely to get ovarian cancer than those who did not have the disease. For women with severe endometriosis, the risk of cancer jumped nearly tenfold.

However, experts cautioned that this still represents a relatively small increase in risk, overall, and that patients with endometriosis shouldn't be unduly concerned.

The study, published July 17 in the journal JAMA, included nearly 78,900 U.S. women with endometriosis. The disease, which affects approximately 10% of reproductive-age women, occurs when tissue similar to the lining of the uterus starts growing outside the organ, triggering iNFLaMMAtion and scarring.

Related: Why is endometriosis so hard to diagnose?

There are different types of endometriosis, which vary depending on whether the wayward tissue grows on the membrane that covers organs in the pelvis, in the ovaries, or on and between other organs in the pelvic and abdominal regions. These types vary in their severity, but in general, endometriosis is strongly associated with pelvic pain, infertility, irritable bowel syndrome, and breast, endometrial and ovarian cancers.

Previously, a study from Finland reported that women with endometriosis had double the chance of getting ovarian cancer and 10 times the risk if they had the form of the disease that affects the ovaries, compared with those without the condition. However, that study lacked enough samples to conduct a detailed analysis of the risks tied to each type of endometriosis.