Executive summary

Clinication outcomes & toxicities of 100 patients treated with proton therapy for chordoma

This study presented efficacy and toxicity outcomes among 100 patients with chordoma treated on the Proton Collaborative Group prospective registry. Locations included base of skull (61%), spine (23%), and sacrum (16%). The median total dose was 74 GyRBE using PS-PBT (13%), US-PBT (54%) and PBS-PBT (33%). The 2/3-year LC, PFS, and OS rates are 97%/94%, 89%/74%, and 89%/83%, respectively. Eight patients experienced acute grade 3 toxicities, most commonly pain (n=3), radiation dermatitis (n=2), fatigue (n=1), insomnia (n=1) and dizziness (n=1). No grade ≥4 acute toxicity nor grade ≥3 late toxicities were reported. The conclusion of this study is that PBT achieved excellent safety and efficacy outcomes with very low rates of treatment failure. CNS necrosis is exceedingly low (<1%) despite the high doses of PBT delivered.