Conditional survival of extremity soft-tissue sarcoma: Results beyond the staging system

BACKGROUND: With increasing interest in adult cancer survivorship, currently available prognostic estimates for long-term survivors of extremity soft-tissue sarcoma (ESTS) are limited. We assessed determinants of survival in adults surgically treated for nonmetastatic ESTS, conditional on specific survival periods. Methods: We identified 6215 persons aged >18 in the Surveillance Epidemiology and End Results program who were surgically treated for nonmetastatic ESTS from 1991 to 2006.We used Cox proportional hazards regression to assess demographic, tumor, and treatment factors associated with 10-year sarcoma-specific survival (SSS) at diagnosis and conditional on surviving 3 and 5 years postdiagnosis. RESULTS: At the time of diagnosis, age, tumor, and treatment factors predicted SSS. Although older age significantly predicted worse SSS for all age groups at diagnosis (HR 3.78 for age >81 vs 18-35; P < .05 for all), the effect of age became nonsignificant as survival time increased, except for the oldest group (>80 years). Tumor size, grade, and histologic subtypes continued to be important predictors of SSS for all periods of conditional survival. Persons who underwent limb amputation were at 3 times the risk of mortality for all conditional survival periods. CONCLUSIONS: In this large population-based experience of ESTS survivors, age >80, tumor, and treatment factors continued to affect long-term survival, whereas the effect of age dampened over time. These estimates provide important counseling information for changing risk factors as survival time increases, help to streamline future surveillance programs, and provide insights into the design of adult survivorship care.