PCOS, or polycystic ovary syndrome, is a syndrome that is caused by hormonal imbalances. Women with PCOS often have higher than normal levels of estrogen all the time because their hormonal cycles are not regular. Over time, high levels of uninhibited estrogen can lead to endometrial hyperplasia, or overgrowth of tissue in the uterus. This overgrowth is more likely to become cancerous than normal endometrial tissue. Thus, although the data varies, it is generally agreed upon by most gynecological societies that due to the high estrogen levels that women with PCOS have, they are at higher risk for endometrial hyperplasia. To reduce this risk, it is often recommended that women with PCOS take hormonal contraceptives to regulate their hormones. Both COCPs and progestin-only methods are recommended. COCPs are preferred in women who also suffer from uncontrolled acne and symptoms of hirsutism, or male patterned hair growth, because COCPs can help treats these symptoms.