INTRODUCTION: Leiomyosarcoma of the kidney and renal pelvis is a rare tumor that, on the basis of limited data, has been ascribed a particularly poor prognosis compared to other subtypes of renal malignancy. Here the population-based Surveillance, Epidemiology, and End Results (SEER) registry is used to study the survival of renal leiomyosarcomas.
METHODS: There were 95,935 cases of invasive cancer of the kidney and renal pelvis retrieved from the SEER registry to provide 112 cases of leiomyosarcoma. Kaplan-Meier survival estimates and Cox proportional hazard models were constructed to compare the survival of leiomyosarcomas to other renal malignancies.
RESULTS: Leiomyosarcomas constituted 0.12% of all invasive renal malignancies. They exhibited a median overall survival of 25 months, with a 25% 5-year overall survival, and a 60% 5-year cause-specific survival. Multivariate analysis of all renal malignancies together revealed that cancer stage was the strongest predictor for overall survival followed by age, histological grade, histological subtype, tumor size, and gender. The hazard ratio for leiomyosarcoma in this analysis was intermediate compared to the other malignancies. When leiomyosarcomas were analyzed separately, the major determinants to overall survival were stage and age at diagnosis. Kaplan-Meier analysis revealed that the overall survival curve for renal leiomyosarcoma essentially superimposed that of transitional cell carcinoma, and was better than that of clear cell carcinoma. These results provide a more optimistic outlook than has been conventionally afforded to this tumor.