Histologic material from 153 cases of uterine tumors with prior diagnosis or suspicion of sarcoma was reviewed. On the basis of cellularity, pleomorphism, and mitotic counts, 81 smooth muscle tumors were divided into 32 leiomyosarcomas, 31 cellular leiomyomas, 17 bizarre leiomyomas, and one intravascular leiomyoma. Only one case among the 153 was lost to follow‐up. The average yearly instance rate for leiomyosarcoma was 0.67 per 100,000 women 20 years old and older. The incidence was significantly higher in Negroes than in Caucasians. The 5‐year survival rate was 20.7%; however, three of the six 5‐year survivors subsequently died of disease, and one is living with disease. Mitotic counts accurately separate leiomyosarcoma from cellular leiomyoma. No patient with fewer than five mitoses per 10 high‐power field died of disease. The average length of follow‐up was 12 years. In spite of the alarming histologic and cytologic features of bizarre leiomyomas no patient died of disease. Follow‐up averaged 11.2 years.

Mixed müllerian tumors of the uterus had an average yearly incidence rate of 0.99 per 100,000 women 20 years old and older in Jefferson County, Kentucky, between 1953 and 1969. The rate was significantly higher in Negroes than in Caucasians. Follow‐up was obtained on all 48 patients. The survival rate on 39 patients followed for 5 years was 20.5%, although one survivor has metastatic disease 15 years following primary treatment. Twenty patients had only homologous elements (carcinosarcoma), while 28 had heterologous elements (mixed mesodermal tumor). There was no statistically significant difference in survival between the two groups, and clinicopathologic features were similar other than the presence of heterologous elements.