Outcomes of osteosarcoma, chondrosarcoma and chordoma treated with image guided-intensity modulated radiation therapy

•Dose-escalated IG-IMRT results in good LC & CSS in OGS, CS and CH of H&N and pelvis.•No significant difference in outcomes for definitive versus post-operative RT.•Significant and sustained benefit in functional outcomes after RT.•Acute & late toxicities were minimal despite escalated doses.•Salvage re-RT is feasible and efficacious in recurrence after dose-escalated IG-IMRT. To evaluate the efficacy and toxicity of dose-escalated image guided-intensity modulated radiation therapy (IG-IMRT) in osteosarcoma (OGS), chondrosarcoma (CS) and chordoma (CH) of head and neck (H&N) and pelvis. In this prospective non-randomized study, 65 patients of H&N or pelvic OGS (24), CS (7) and CH (34) mandating definitive or post-operative radiotherapy from May 2013 to December 2018 were included. Radiotherapy doses in definitive setting were 72.0 Gy for CH and 70.2 Gy for OGS and CS; while in post-operative setting it was 66.6 Gy and 64.8 Gy respectively (at 1.8 Gy per fraction). Planned doses of radiotherapy could be completed in 61 (93.8%) patients; with grade III or higher acute and late toxicities of 3% and 0% respectively. With a median follow-up of 52 (range 6–92) months, the five-year actuarial local control (LC) rates were 66% in OGS, 38.1% in CS and 75.9% in CH; while cause-specific survival (CSS) rates were 54.7%, 64.3% and 92.2% respectively. There was no statistically significant difference in outcomes for patients receiving definitive and post-operative radiotherapy. Locally controlled disease at first follow-up after radiotherapy was associated with improved CSS and OS in CS (p = 0.014) and CH (p