Endometrial cancer classification

Classification
Most endometrial cancers are carcinomas (usually adenocarcinomas), meaning that they originate from the single layer of epithelial cells which line the endometrium and form the endometrial glands. There are many microscopic subtypes of endometrial carcinoma, including the common endometrioid type, in which the cancer cells grow in patterns reminiscent of normal endometrium, and the far more aggressive papillary serous and clear cell endometrial carcinomas. Some authorities have proposed that endometrial carcinomas be classified into two pathogenetic groups:

Type I:
These cancers occur most commonly in pre- and peri-menopausal women, often with a history of unopposed estrogen exposure and/or endometrial hyperplasia. They are often minimally invasive into the underlying uterine wall, are of the low-grade endometrioid type, and carry a good prognosis.

Type II:
These cancers occur in older, post-menopausal women, are more common in African-Americans, and are not associated with increased exposure to estrogen. They are typically of the high-grade endometrioid, papillary serous or clear cell types, and carry a generally poor prognosis

In contrast to endometrial carcinomas, the uncommon endometrial stromal sarcomas are cancers which originate in the non-glandular connective tissue of the endometrium. Malignant mixed müllerian tumor is a rare endometrial cancer which contains cancerous cells of both glandular and connective tissue appearance - in this case, the cell of origin is unknown.