Pelvic Location Predicts Worse Outcomes in Alveolar Rhabdomyosarcoma: Underuse of Radiotherapy and Missed Survival Benefit

Introduction Alveolar rhabdomyosarcoma (ARMS) is a rare, aggressive soft‐tissue malignancy occurring mostly in children. Pelvic presentation poses diagnostic and therapeutic challenges due to proximity to critical structures. This study aims to assess the prognostic treatment factors associated with pelvic ARMS. Methods We conducted a retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) database (2000–2021) that included patients with ARMS. Variables included demographics, socioeconomic factors, and treatment modalities. Logistic regression evaluated associations between tumor location and treatment receipt. Cancer‐specific mortality was analyzed using Cox proportional hazards regression, with Weibull parametric survival analysis performed to quantify survival time benefits. Results The study included 678 ARMS patients (585 non‐pelvic vs. 93 pelvic). Patients with pelvic tumors had significantly higher mortality risk (hazard ratio [HR] = 1.44, 95%‐confidence interval [95% CI]: 1.08–1.94, p = 0.014) and were less likely to undergo resection (45.1% vs. 30.1%, p = 0.007). Weibull parametric analysis demonstrated radiation therapy was associated with improved survival in pelvic tumors, with patients receiving radiation having a predicted median survival of 34.7 months compared to 17.0 months for those not receiving radiation (17.7 month difference, p = 0.039). Both radiation therapy (HR = 0.56, 95% CI: 0.43–0.71, p < 0.001) and surgery (HR = 0.61, 95% CI: 0.48–0.78, p < 0.001) were independently associated with decreased cancer‐specific mortality. Conclusions Radiation therapy demonstrated a significant survival benefit in pelvic ARMS, emphasizing the need for standardized treatment strategies in high‐risk sites.