Tumour control and Quality of Life in children with rhabdomyosarcoma treated with pencil beam scanning proton therapy.

Abstract Purpose To assess clinical outcomes in children with rhabdomyosarcoma (RMS) treated with pencil beam scanning (PBS) proton therapy (PT). Methods and materials Eighty-three RMS (embryonal, n =74; 89%) patients treated between January 2000 and December 2014 were included. The median age was 4.5years (range, 0.8–15.5). All patients received systemic chemotherapy according to prospective protocols. Patients had low-, intermediate-, and high-risk disease in 24%, 63%, and 13% of cases, respectively. The median total dose delivered was 54Gy(RBE) (range, 41.4–64.8). Results After a median follow-up time of 55.5 months (range, 0.9–126.3), local failure occurred in 16 patients. The 5-year local-control survival rate was 78.5% [95% confidence interval (CI), 69.5–88.5%]. Significant predictors for local failure were group/stage, tumour location, and size. Fourteen patients (16%) died, all from tumour progression. The 5-year overall survival was 80.6% (95%CI, 71.8–90.0%). The 5-year incidence of grade 3 non-ocular late toxicity was 3.6% (95%CI, 1–12%). No grade 4–5 late toxicities were observed. One radiation-induced malignancy was observed (1.2%). The Quality of Life (QoL) scores increased significantly after PT compared to baseline values. Conclusions PBS PT led to excellent outcome in children with RMS. Late non-ocular toxicity was minimal and QoL good.