1696-1697 / 2605
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 at 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.