The Estrogen Factor
Hormone levels play a big role when it comes to cancer risk — particularly types of uterine cancer like endometrial cancer. Women with PCOS and other factors that increase estrogen levels — including obesity, diabetes, or taking medications like tamoxifen (Nolvadex, Tamosin, Tamofen, Tamoxen) or estrogen replacement therapy — are more likely to develop endometrial cancer than those without these factors. The abnormal amounts of estrogen are particularly risky when not balanced by sufficient progesterone levels in the blood. This is why post-menopausal women who have not had a hysterectomy and who need treatment for severe menopausal symptoms will be prescribed both estrogen and progesterone, instead of estrogen alone.
Progesterone is the hormone responsible for the monthly “shedding” process of the endometrium — or the lining of the uterus. This process results in monthly menstruation, which many women with PCOS don’t have because of insufficient progesterone levels. Without progesterone and monthly periods, the endometrium becomes thick and the cells may become altered, leading to a precancerous condition called endometrial hyperplasia. Eventually, endometrial cancer may develop if PCOS is left untreated.