According to estimates by the American Cancer Society, U.S. physicians will diagnose 49,560 cases of uterine cancer in 2013. Typically, this type of cancer originates in the endometrium, or lining of the uterus. Endometrial carcinomas can be classified as one of two kinds. The most common form, Type I malignancies, typically present in early stages in pre- and peri-menopausal women, are associated with prolonged estrogen exposure, and have a good prognosis. Type II tumors occur in post-menopausal women, appear in more advanced stages, are not linked to estrogen, and have a worse prognosis. The two types also differ in their molecular structure.