Adjuvant radiation therapy for resectable retroperitoneal soft tissue sarcoma: the University of Florida experience.

Background: In the management of retroperitoneal sarcomas it is necessary to achieve local control to ensure survival. The role of adjuvant radiation therapy (RT), either pre- or postoperative, remains controversial.
Methods: Outcomes for 40 patients with retroperitoneal sarcoma treated with surgery and postoperative RT (n = 25) or preoperative RT (n = 15) were analyzed for variables prognostic for local control, survival, and associated complications.
Results: Patterns of failure for patients treated by resection and postoperative RT were local (n = 4), local and distant (n = 3), and distant (n = 3). The failure patterns for preoperative RT cases were local (n = 2), local and distant (n = 2); and distant (n = 4). Median time to local recurrence in the postoperative and preoperative RT series were 1 year and 2.5 years respectively. The margin status was predictive for local control (P = 0.0065) and survival (P = 0.0012), regardless of treatment sequence. Absolute 5-year survival was 12% with positive margins versus 69% if negative. Histologic grade was indicative of the risk for distant metastasis (low grade 8% vs high grade 64%; P = 0.1373), and significantly predicted 5-year absolute survival (low grade 77% vs high grade 34%; P = 0.0267). Postoperative RT was associated with significant complications (infection, hemorrhage, and bowel obstruction--2 cases each).
Conclusion: Compared with the surgery-alone series, adjuvant RT appears to improve the probability of local control. Preoperative RT may be the preferred sequence potentially to improve tumor resectability and local-regional control with less risk of complications than with postoperative RT.