Role of radiotherapy to primary/metastatic sites in pediatric patients with metastatic rhabdomyosarcoma in the BERNIE study.

Abstract

10541 Background: Local control is a key part of treatment of local/locoregional rhabdomyosarcoma (RMS) and often involves radiotherapy (RT) with/without surgery. The role of RT in metastatic RMS is uncertain, with little published evidence to guide clinicians. We analyzed data from the BERNIE trial to assess the benefit of RT for patients (pts) with metastatic RMS. Methods: In the BERNIE study (NCT00643565) pts aged ≥6 months to <18yrs with metastatic RMS and non-RMS soft tissue sarcoma were randomized to receive chemotherapy (CT) with/without bevacizumab (BEV), surgery, and/or RT (at cycle 6–9) then maintenance CT. RT was recommended for all sites of metastases if feasible (investigator discretion allowed, resulting in variability in actual RT given). Pts were categorized into those receiving: RT all sites, partial RT, no RT. Event-free survival (EFS) and overall survival (OS) were calculated using Cox proportional hazards models and a landmark approach: only pts who were event free at day 221 (i.e. end of cycle 9 + 1 month) were included (EFS, n=85; OS, n=97). Variables adjusted were: treatment (as randomized), disease type (alveolar/embryonal/other), risk group, age >10yrs, metastatic lesion count (1, 2–3, 4+). The analysis was non-randomized, exploratory and post hoc. Results: Of 102 pts with RMS, 22 received no RT, 49 partial RT, and 31 RT to all sites. Baseline characteristics were mostly balanced, and comparable proportions of pts received BEV. Better OS was observed in the RT group (Table) (comparable with unadjusted results). A non-significant EFS improvement was observed for the RT groups. Conclusions: Partial RT and RT to all sites of disease in metastatic RMS was associated with significant OS benefits, albeit in small pt numbers. This should be confirmed in a prospective randomized trial. Clinical trial information: NCT00643565. [Table: see text]