Spontaneous endomyometrial neoplasms in aging Chinese hamsters.

Twenty-one endomyometrial neoplasms among 93 nulliparous noninbred Chinese hamsters were evaluated. The median survival time of the 93 females was 1,040 days. The median age of hamsters with endomyometrial neoplasms was 1,200 days. Neoplasms were classified as carcinoma or malignant mixed müllerian tumors of the endometrium and benign or malignant myometrial neoplasms. There were 13 endometrial adenocarcinomas. Three tumors were mixed adenosquamous carcinomas, which occurred in significantly older Chinese hamsters than did adenocarcinomas. Three malignant mixed müllerian tumors consisted of 2 carcinosarcomas and 1 mixed mesodermal tumor. The 2 myometrial neoplasms were a leiomyoma and a leiomyosarcoma. The classification and relative frequency of these neoplasms were similar to endomyometrial neoplasms of women, which makes Chinese hamsters useful subjects for studies of spontaneous endomyometrial cancers.