Outcomes for pediatric patients with osteosarcoma treated with palliative radiotherapy.

Background Few studies have addressed the efficacy of palliative radiotherapy (RT) for pediatric osteosarcoma (OS), a disease generally considered to be radioresistant. We describe symptom relief, local control, and toxicity associated with palliative RT among children with OS. Procedure Patients diagnosed with OS at age 18 and under and treated with RT for palliation of symptomatic metastases or local recurrence at the primary site from 1997 to 2017 were included. We retrospectively reviewed details of RT, symptom improvement, local control, survival, and toxicity. Results Thirty-two courses of palliative RT were given to 20 patients with symptomatic metastatic and/or locally recurrent primary disease. The median equivalent dose in 2 Gy fractions (EQD2) was 40.0 Gy (range, 20.0-60.4). The median number of fractions per course was 15 (range, 5-39). Symptom improvement occurred in 24 (75%) courses of RT at a median time of 15.5 days (range, 3-43). In nine courses (37.5%), symptoms recurred after a median duration of symptom relief of 140 days (range, 1-882). Higher EQD2 correlated with longer duration of response (r = 0.39, P = 0.0003). Imaging revealed local failure in 3 of 14 courses followed with surveillance imaging studies (21.4%). The median time to progression was 12.9 months (range, 4.4-21.8). The median follow-up time following the first course of palliative RT was 17.5 months (range, 1.74-102.24), and median time to overall survival was 19.4 months. Toxicity was mild, with grade 2 toxicity occurring in one course (3.1%). Conclusions RT is an effective method of symptom palliation for patients with recurrent or metastatic OS, with higher delivered dose correlating with longer symptom relief and with little associated toxicity.