There is no conclusive evidence that having polycystic ovary syndrome (PCOS)* is associated with risk of endometrial cancer. Only a small number of studies have been done to date and these have been of poor quality.

PCOS is associated with known endometrial cancer risk factors, such as obesity, diabetes, and metabolic syndrome. It is possible that this association results in an increase in risk of endometrial cancer in women with PCOS. It is also possible that PCOS itself results in an increased risk of endometrial cancer due to effects on the body’s metabolism.

Other factors that are common in women with PCOS, such as not having children, age at first pregnancy, use and/or length of use of hormone replacement therapy or oral contraceptives, may also affect risk of endometrial cancer. This makes the results of studies difficult to interpret.

* Polycystic ovary syndrome is a condition that affects around 8–13% of women during their reproductive years. Symptoms include irregular or no menstrual periods, difficulty getting pregnant, pelvic pain, skin and hair changes, and cysts on the ovaries.