How Endometriosis and Ovarian Cancer May Be Linked

Medically Reviewed By William C. Lloyd III, MD, FACS
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Female doctor discussing with a patient

Women who have endometriosis may worry about complications. These often include pain and not being able to have children. But is cancer of the ovaries also a concern? There is still much that experts don’t understand, but research does point to a link between the two conditions.

About 5 million women in the United States have endometriosis. About 1 in 75 women gets ovarian cancer. Some research suggests that women with endometriosis may be 2 to 3 times more likely to develop ovarian cancer.

Shared Risk Factors

Some risk factors apply to both endometriosis and cancer. That may help explain the link. For instance, the hormone estrogen seems to increase the risk of endometriosis. Research also suggests that women using estrogens after menopause have an increased risk of developing ovarian cancer. The risk is greater for women who have taken estrogen alone (without progesterone) for at least 5 to 10 years.

Another shared risk factor is infertility. Up to 40% of women with endometriosis struggle with fertility. Infertility and never having given birth to a child are also risk factors for cancer of the ovaries.

Endometriosis in Cancer Cells: EAOCs

There are types of cancer called endometriosis-associated ovarian cancers (EAOCs). These are more common in younger women who have not yet entered menopause. Doctors usually can diagnose EAOCs at an early stage and before the cancer has spread very far.

Women with an EAOC are also more likely than others to develop another type of cancer. Endometrial cancer is most common. Endometrial cancer begins in the endometrium—the lining of the uterus.

Understanding the Theories

There are a few theories about why women with endometriosis are at a greater risk of developing ovarian cancer.

Inflammation could be part of the problem. It plays a role in many types of cancer. In endometriosis, inflammation may cause the growth of tissue outside the uterus. The changes in individual cells that develop because of this inflammation may help explain the endometriosis-cancer connection.Most women with endometriosis will not develop cancer. But, if you have endometriosis and are concerned, talk with your doctor about your risk. Your individual risk of ovarian cancer depends on several factors, including a family history of cancer. Being aware of your risks can help with prevention and spotting cancer early. And that gives you a better chance of beating it.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Dec 10
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