[Biological behavior of smooth muscle tumors of the alimentary tract--a pathological analysis of 501 cases].

501 cases with smooth muscle tumors of the alimentary tract are presented with follow up information. 249 leiomyomas and 252 leiomyosarcomas were analyzed in an attempt to evaluate their biological behavior. All patients with leiomyoma survived except 15 who died of other diseases. In the leiomyosarcoma group, 134 survived and 118 died. The 1-2-3-4-5-10-and over 10 year-survival rates were 80.4%, 62.0%, 48.7%, 41.5%, 36.1%, 30.1% and 15.1%, respectively. The following factors were found to be statistically prognostic, arranged in order of their influence on survival; histologic grade, tumor size, mitotic rate and location of the tumor. Leiomyosarcomas were histologically divided into three grades; the higher the grade, the poorer the prognosis. The prognosis was better when the sarcoma was smaller and became worse when larger, especially over 10 centimetres in diameter. The survival rate decreased with increase in mitotic figure. Patients with leiomyosarcoma in the esophagus or stomach had longer survival than those with lesions in the small or large intestines.