Endometrioid Adenocarcinomas of the Uterine Corpus in Women Younger Than 50 Years of Age Can Be Divided into Two Distinct Clinical and Pathologic Entities Based on Anatomic Location

Background: This study used the clinicopathologic profiles of Japanese women younger than 50 years of age with endometrial carcinoma to distinguish the clinicopathologic features of carcinomas of the lower uterine segment (LUS) from those of carcinomas of the corpus mucosa proper (CMP).

Methods: Eighty-eight endometrial carcinomas in women younger than 50 years old (25.3%) were selected from our file of 348 Japanese women with endometrial carcinoma. Seventy-two were classified as carcinomas of the CMP and 16 carcinomas of the LUS. A tumor was judged to be a carcinoma of the LUS when it involved a continuous area ranging from the lower corpus to the upper cervix with or without intervention of a portion of uninvolved LUS.

Results: The mean ages of women with carcinomas of the CMP and LUS were 41.2 and 39.0 years, respectively. In comparison to carcinomas of the LUS, carcinomas of the CMP were more strongly associated with reproductive risk factors including parity (P = 0.01) and polycystic ovary syndrome (P = 0.02). There was no significant difference in body mass index or the incidence of diabetes mellitus and hypertension between women presenting with carcinomas of the CMP and LUS. Histologically, carcinomas of the LUS more frequently showed a high-grade endometrioid tumor (P = 0.02) with deep myometrial invasion (P < 0.01) and were less associated with endometrial hyperplasia (P < 0.01) than those of the CMP.

Conclusions: Carcinomas of the LUS occurred predominantly in women younger than 50 years of age and had clinicopathologic features distinct from carcinomas of the CMP in women younger than 50 years of age.