Is There a Link Between Endometriosis and Ovarian Cancer?

Peter Kovacs, MD, PhD


March 28, 2014


This study found an increased risk for ovarian cancer among infertile women with endometriosis. Endometriosis can be diagnosed in about 10%-15% of women and in 30%-40% of the infertile population.[6] Therefore, a 3- to 8-fold increased risk, even if based on relatively few cases, is significant.

Many groups looked for an association between ovarian cancer and fertility treatment. The results so far have been mostly reassuring. Compared with the general population, a slightly increased risk was seen among those with infertility who had been exposed to treatment, but the risk was primarily limited to nulliparous women. Within the infertile cohort, the use of gonadotropins typically was not associated with an increased risk compared with those not exposed.[7,8,9] Most studies suffer from methodological issues, such as lack of controlling for confounding variables, short follow-up, a limited number of cancer cases, and incomplete data collection.

Endometriosis is known to be associated with inflammatory changes that could induce malignant changes. Endometriosis is often associated with infertility and nulliparity could further increase the risk. One of the strengths of the current study is that most endometriosis cases were confirmed by operative or histology reports. Women who self-reported endometriosis without surgical confirmation were also enrolled, but excluding them from the analysis would not have significantly changed the direction of the associations.

Contraceptive pills are often used to manage the various problems associated with endometriosis. In this study, women who took oral contraceptives for more than 5 years were at lower risk of developing ovarian cancer. Oral contraceptive use is known to be associated with an up to 50% risk reduction for ovarian cancer.[10] It appears that a similar beneficial effect can be seen among those with endometriosis. This benefit should further be explored.

Many women with endometriosis require surgery to manage their symptoms; this may involve ovarian surgery, or potentially, oophorectomy. This certainly would have a significant impact on their future ability to conceive. On the basis of the findings of the current study, infertile women with endometriosis are at an increased risk for ovarian cancer. One could consider elective oocyte or embryo cryopreservation to allow them to maintain fertility, should radical surgery be needed to manage their symptoms.



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