Abstract
Rhabdomyosarcoma (RMS) is rare in adulthood, accounting for 2%-5% of adult soft tissue tumors, and less than 20% occur in genitourinary organs. Given its rarity, survival data on adult kidney, bladder, and prostate RMSs is limited. In this population-based analysis, we performed an analysis of all adult RMS cases reported in Surveillance, Epidemiology, and End Results (SEER) database to understand prognostic factors among kidney, bladder, and prostate RMS. A query of the SEER database was performed from 1973 to 2016 for patients >18 of age with RMS. The final cohort consisted of 14 kidney, 35 bladder, and 21 prostate RMS cases in the adult population. Demographic, treatment, and survival data were obtained. Analysis was performed using Fisher's exact test, survival analysis, and model. The median (range) age of diagnosis for adult bladder RMS was 65 years old (19-84) compared to 52.5 (28-68) and 42 (19-87) for kidney and prostate (p = 0.007). About 78.6% of patients underwent surgical intervention. Five-year overall survival (OS) for adult kidney, bladder, and prostate RMS are 17.1% (2.9-41.6%), 22.2% (9.4-38.4%), and 33.0 (12.8-55.0%), respectively. OS was not statistically associated with primary site (p = 0.209). On multivariable analysis, compared to adult bladder RMS, kidney RMS had a higher incidence of mortality (HR: 2.16, 95% CI 1.03-4.53, p = 0.041). Incidence of mortality from prostate RMS was not significantly different from bladder RMS (HR: 0.70, 95% CI 0.30-1.65, p = 0.411). Extent of disease (HR: 5.17, 95% CI 2.09-12.79, p < 0.001) and older age (HR 1.03, 95% CI 1.01-1.04, p = 0.002) were adverse prognostic factors for OS. Overall survival at 5 years for adult kidney, bladder, and prostate RMS is poor. Localized disease and younger age are prognostic factors for improved outcomes in adult RMS. Hence, early diagnosis and intervention appear paramount to improved survival for this rare malignancy in adulthood.