Clinical characteristics and long-term outcomes of rhabdomyosarcoma in Korean children, adolescents and young adults: a single-center experience.

Purpose: This study aimed to analyze characteristics, treatment, long-term outcomes, and prognostic factors for children, adolescents and young adults with rhabdomysosarcoma (RMS).

Methods: This retrospective historical study included 75 patients with RMS treated between 2002 and 2019. Clinical data and follow-up results were collected including all diagnosis, treatment and prognosis information.

Results: Patients median-age-at-diagnosis was 6 years. Embryonal and alveolar histology occurred in 51 (68.0%) and 21 (28.0%) patients, respectively. The tumors most frequently originated from parameningeal site (28.0%). Of 74 evaluable patients for treatment outcome, 60 (81.1%) achieved complete response for first-line treatment, of whom, 34 (56.6%) maintained complete response, 26 (43.3%; 23/26, local relapse) showed relapse. Of 40 patients with treatment failure, 16 and 6 occurred in parameningeal area and retroperitoneum/perineum, respectively. The 5-year progression-free survival (PFS) and overall survival (OS) were 45.0% and 64.5%, respectively. In multivariate analyses, parameningeal site (p = 0.027), no gross total resection (p = 0.047), and no radiation therapy (RT) (p < 0.001) for PFS; and parameningeal site (p < 0.001) and no RT (p = 0.010) for worse OS, were significant. The median PFS and OS from treatment failure date in 40 patients with primary treatment failure were 1.3 and 4.1 years, respectively. Of 26 patients with relapse, interval to relapse < 7 months, retroperitoneum/perineum site, TNM stages III/IIV, and no salvage RT were independently associated with OS.

Conclusion: The importance of adequate local therapy was highlighted in RMS treatment. Treatment failure was largely a local failure. Whether as a component of initial or salvage treatment, RT could improve patients' survival.