Demographics, stage distribution, and relative roles of surgery and radiotherapy on survival of persons with primary prostate sarcomas.

BACKGROUND: Primary prostate sarcomas (PPS) are rare. Outcomes for this cancer have not been well characterized.

MATERIALS AND METHODS: Subjects with a PPS diagnosed between 1973 and 2014 were identified in the SEER database. Subjects were stratified by disease stage and types of therapies received. Disease-specific survival (DSS) and Overall survival (OS) was estimated by Kaplan-Meier analysis and cohorts were compared with a univariate and multivariable Cox regression.

RESULTS: The incidence of PPS among all prostate cancer diagnoses was 0.02%. Subjects younger than age 26 years at diagnosis represented 29% of cases, and 32% of primary prostate sarcomas were rhabdomyosarcoma histology.

RHABDOMYOSARCOMA HISTOLOGIES: The median age at diagnosis was 9 years. Between age 0-25 years rhabdomyosarcoma accounted for 96.4% of primary prostate sarcoma diagnoses, after age 25 rhabdomyosarcoma represented 15% of new diagnoses. The 10-year DSS and OS for rhabdomyosarcoma was 47% and 44%.

NON-RHABDOMYOSARCOMA HISTOLOGIES: The median age at diagnosis was 71 years. The most common diagnoses were leiomyosarcoma (33%) and carcinosarcoma (28%). Localized, regional, or distant disease occurred in 40%, 34%, and 26% of cases. The 10-year DSS and OS were 26% and 14%. In locally advanced cases, RT added to surgery trended toward improved DSS (P = 0.10).

CONCLUSIONS: Disease-specific survival and OS for non-rhabdomyosarcoma histologies appear inferior to those of rhabdomyosarcoma. The addition of RT to surgical resection may improve DSS in locally advanced non-rhabdomyosarcoma. This is the largest report of the incidence, stage distribution, and survival for this extremely rare urologic malignancy providing valuable prognostic information.