Definition

A rare type of cancer that forms in the connective tissue of the lining of the uterus. It may also form in the ovaries, cervix, and vagina, but this is very uncommon. ESSs may be low grade or high grade, depending on how abnormal the cancer cells look under a microscope and how quickly the cancer cells are likely to grow and spread. They usually occur before menopause in women between 40 and 50 years of age. Also called endometrial stromal sarcoma.