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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 started to accrue to that dose.