Particle Therapy 2017

Phase I trial of pre-opera0ve intensity modulated proton radia0on (IMPT) with simultaneous boost to high risk margin for retroperitoneal sarcomas DeLaney et al. MGH – Abstract for PTCOG 2016 Goal: selec>vely escalate retroperitoneal sarcoma (RPS) preopera>ve radia>on dose to tumor volume (CTV2) judged at high risk for posi>ve margins, aiming to reduce local recurrence(LR). ➢ Pa>ents > 18 years with primary or locally recurrent RPS ➢ preopera>ve IMPT, 50.4 GyRBE/28 frac>ons, to CTV1 (GTV and adjacent >ssues) with integrated boost to CTV2 to doses of 60.2, 61.6, and 63.0 GyRBE in 28 frac>ons of 2.15, 2.20, and 2.25 GyRBE respec>vely. ➢ Phase I study primary objec>ve was determina>on of maximum tolerated dose (MTD) to CTV2, to be further tested in subsequent phase II. Results: ➢ 11 pa>ents were accrued to increasing IMPT dose levels without acute dose limi>ng toxici>es preven>ng dose escala>on to MTD. ➢ Acute toxicity mild. No radia>on interrup>ons. No unexpected periopera>ve morbidity. ➢ 8 months postopera>vely, one pa>ent developed hydronephrosis treated by stent; Ureter received 57.5 GyRBE. Subsequently constrained to 50.4 GyRBE. ➢ With 18-month median follow-up, there were no LRs. Conclusions: IMPT dose escala>on to CTV2 to 63 GyRBE achieved without DLT; phase II IMPT study will accrue to that dose. Possible shia in Paradigm from CTV to 50 Gy preopera>vely– 3 weeks wait – surgery – 2-3 weeks wait – boost for posi>ve margins or gross residual To CTV and posi>ve margin volume (CTV2) preop. Postop. boost for gross residual only.