Association of perioperative radiation therapy with outcome in 204 patients with primary retroperitoneal sarcoma: A two-institution study.

Abstract

10520 Background: Radiation therapy (RT) for retroperitoneal and pelvic sarcomas (RPS) is controversial. We examined the association of perioperative, advanced modality RT on outcomes in primary RPS. Methods: Prospectively maintained databases were reviewed to compare primary RPS patients (pts) treated at two institutions between 2003 and 2011. Clinicopathologic variables were analyzed with endpoints of local recurrence-free survival (LRFS) and disease-specific survival (DSS). Results: At one institution 172 pts were treated with surgery alone while at the other 32 pts were treated with surgery and perioperative proton beam or intensity-modulated RT ± intraoperative RT. The groups were similar in age, gender, tumor grade, tumor size, and margin status (p = NS). The RT group had a lower percentage of retroperitoneal versus pelvic tumors and leiomyo/liposarcoma versus other histologies (p < 0.05). Median follow-up was 38.7 months (36.9 for RT group, 38.8 for surgery alone). Five-year predicted LRFS was 91% (95% CI, 79-100%) in the RT group and 65% (57-74%) in the surgery only group (p = 0.06). RT was marginally significant in univariate analysis of LRFS. Upon adjusting for univariate predictors, RT was significantly associated with better LRFS (p = 0.046; Table). Five-year predicted DSS was 93% (95% CI, 82-100%) in the RT group and 84% (78-91%) in the surgery-only group (p = 0.25). The only independent predictor of DSS was age. Morbidity was higher in the RT group (41% vs 17%; p= 0.004). Conclusions: In this retrospective study, the addition of advanced modality RT to surgery for primary RPS was associated with a reduced risk of local recurrence, although this did not translate into a statistically significant improvement in DSS. This treatment strategy warrants further investigation in a randomized trial. [Table: see text]