What Is the Link Between Endometriosis and Ovarian Cancer?

Endometriosis is a chronic condition in which endometrial-like cells resembling those inside the uterus grow elsewhere in the body. People with endometriosis may have pelvic pain, painful periods, and difficulty becoming pregnant.

Ovarian cancer also involves abnormal tissue growth that can affect the reproductive system. Unlike the endometrial cells in endometriosis, ovarian cancer growths are not benign. They can damage healthy cells and spread to other parts of the body.

Although ovarian cancer and endometriosis have similar symptoms, ovarian cancer symptoms are less likely to be related to the menstrual cycle.

Read on to learn about similarities between the two conditions, how to distinguish them, and how and to what extent endometriosis contributes to ovarian cancer risk.

What Similarities Do Endometriosis and Ovarian Cancer Share?

Endometriosis is common. To give a prevalence statistic, an estimated 11% of women aged 15 to 44 in the USA have undiagnosed endometriosis.

When people have endometriosis, growths resembling endometrial tissue develop outside the uterus. These grow on pelvic organs such as the ovaries and peritoneum (abdominal lining).

Endometriotic tissue may lead to scarring and adhesions that can damage or obstruct reproductive organs.

Although these growths are benign, endometriosis still shares similarities with ovarian cancer, which causes cancerous growths. Like ovarian cancer, endometriosis can increase in size over time and damage surrounding organs.

Because both conditions cause abnormal growths in the pelvic area, they may share symptoms such as pain, pressure, and bloating in that region.

How Is It Diagnosed: Endometriosis or Ovarian Cancer?

Some symptoms of endometriosis resemble ovarian cancer symptoms, but the conditions have distinct differences.

What are the symptoms of endometriosis?

Endometriosis generally affects people who are actively menstruating. In rare cases, however, people may have endometriosis after menopause and after a hysterectomy (surgical removal of the uterus).

Symptoms include:

• severe pain in the lower abdomen
• bloating
• period/menstrual pain
• pain during or after sexual intercourse
• nausea, diarrhea, or constipation during periods
• blood in the urine during periods
• painful bowel movements or pain when urinating during periods

Endometriosis is a progressive disease, meaning it may worsen over time. It can adversely affect fertility, making pregnancy difficult.

What are the symptoms of ovarian cancer?

Although ovarian cancer can affect any woman with ovaries, it is most common after menopause. However, in people with a family history of breast and ovarian cancer, the risk is markedly higher, and it may occur at an earlier age.

- Related topic: How should people with a hereditary risk of ovarian cancer be monitored?

Ovarian cancer is also slightly more common in people with endometriosis than in the general population.

Although ovarian cancer generally has no symptoms in its early stages, its most common symptoms include:

• persistent abdominal bloating
• stomach pain that does not go away
• the urge to urinate more often than usual
• difficulty eating and a feeling of fullness
• changes in bowel habits, such as needing to pass stools more or less often than usual
• fatigue
• unexplained weight loss

Does Endometriosis Cause Ovarian Cancer?

Although endometriosis does not necessarily cause ovarian cancer, research shows that women with endometriosis have a slightly higher ovarian cancer risk than those without the condition.

One study showed that people with endometriosis had a 1.7-fold higher risk of ovarian cancer than the general population. However, the researchers emphasize that a causal relationship is unclear.

Endometriosis is a common but frequently missed diagnosis. Many women have the condition without knowing it or receiving a diagnosis. A definitive diagnosis also requires a laparoscopic procedure to remove abnormally located endometrial tissue and perform a biopsy.

Although it is unclear how much endometriosis increases cancer risk, there is clearly a link between the conditions. Endometriotic tissue may modestly increase cancer risk by:

• producing a high concentration of estrogen, which may promote tumor growth
• tumor-suppressor ARID1A gene mutations
• displacement of endometrial cells toward the pelvis with menstrual flow that becomes disrupted over time

Other research suggests that endometriosis may precede type 1 epithelial ovarian cancers in some people. This may result from gene mutations contributing to abnormal tissue and tumor growth.

However, scientists working in this area do not yet understand the link between these two conditions, and more research is needed to discover whether and how endometriosis may cause ovarian cancer.

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