Does combined dose intensification radiotherapy improve disease control in resectable retroperitoneal sarcoma? Long-term results of a phase I/II trial.

Abstract

10050 Background: Late failure is a challenging problem in retroperitoneal sarcoma (RPS) and reported 10 yr overall survival (OS) rates range from 20-30%. Use of preoperative external beam radiotherapy (XRT) in the management of RPS remains controversial. No RCT and very few prospective trials of any type have been completed. We investigated the effects of preop XRT plus dose escalation with early postop brachytherapy (BT) on long term survival and recurrence in RPS. Methods: From 06/96 to 10/00, 40 patients (25 female) with resectable RPS were entered onto a phase I/II trial of preop XRT (50 Gy) plus postop BT (20-25 Gy). As previously reported, BT to the upper abdomen was associated with significant grade III-V postop toxicity, and from 12/98 on, BT was applied only to cases where the “field at risk” excluded the upper abdomen. Kaplan Meier survival curves were constructed; OS and recurrence free survival (RFS) were compared by log rank (SPSS 19.0). Results: Median age at study entry was 58 (38-70) yrs. Twenty nine patients presented to our center with primary disease (73%), and 22 (55%) had high grade tumors. All patients had preop XRT and total gross resection, while half (n=19) received BT. As of 12/2011, median follow-up time is 108 mos. For the entire study cohort, OS at 5 and 10 yrs were 70% and 65%, respectively; RFS at 5 and 10 yrs were 65% and 58%, respectively. RFS at 5 yrs was reduced in high vs. low grade RPS (50% vs. 83%, p=0.028), but by 10 yrs. was similar in high and low grade tumors (50% vs. 67%, p=ns). RFS was reduced in patients who presented with recurrent vs. primary disease (27% vs. 69% at 10 yrs., p=0.018), as was OS (36% vs. 76% at 10 yrs., p=0.034). Neither OS nor RFS was improved in the cohort of patients who received BT compared to the cohort who did not: at 10 yrs. RFS was 53% +BT and 62% -BT, while OS was 53% and 76%, respectively, p=ns. Conclusions: In this prospective study with mature follow-up, long term OS and RFS in patients who underwent combined preop XRT plus resection of RPS compare favorably with those reported in retrospective institutional and population-based series. Postoperative BT did not contribute to disease control.