A case-control analysis found that radiotherapy (RT) delivered either pre- or postoperatively improved overall survival compared with surgery alone in patients with retroperitoneal sarcoma.
“The anatomic constraints of the retroperitoneum often make complete resection difficult, and incomplete (R1 or R2) resection has been reported in up to half of patients who undergo surgery with curative intent,” wrote study authors led by Daniel Nussbaum, MD, of Duke University Medical Center in Durham, North Carolina. Perioperative RT is often used to decrease locoregional recurrence in this malignancy, but data on its use are limited.
To fill that gap, the authors did two case-control, propensity score–matched analyses of patients included in the National Cancer Data Base (NCDB)—one comparing those who received preoperative RT with no RT, and the other comparing postoperative RT with no RT. In total, there were 563 patients in the preoperative RT group, 2,215 in the postoperative RT group, and 6,290 in the no RT group. The results were published in Lancet Oncology.
All patients had localized, primary retroperitoneal sarcoma, and were diagnosed between 2003 and 2011. In the preoperative RT comparison, the median overall survival was 110 months with RT and 66 months without RT. Preoperative RT was significantly associated with a survival advantage, with a hazard ratio (HR) of 0.70 (95% CI, 0.59–0.82; P < .0001).
Similarly, postoperative RT patients had a median overall survival of 89 months, compared with 64 months with no RT. This was again significant, with an HR of 0.78 (95% CI, 0.71–0.85; P < .0001). Five-year survival rates were also better with both pre- and postoperative RT than with no RT. A sensitivity analysis was conducted to include the extent of resection and surgical margin, neither of which changed the effect size for RT in meaningful fashion.
Interestingly, treatment at academic medical centers was significantly associated with increased preoperative RT use and decreased postoperative RT use. Also, preoperative RT was more frequently used in the 2007–2011 period than in 2003–2006.
The authors noted that the retrospective nature of the study does limit its interpretation, as does the specific data limitations of the NCDB (patterns of recurrence, and recurrence-free and disease-specific survival are not included).
In spite of those limitations, though, the authors concluded that, “These findings support the increasing use of perioperative RT for patients with retroperitoneal sarcoma.” Which specific patients derive the most benefit remains unknown, however; an ongoing European Organisation for Research and Treatment of Cancer trial will shed light on that question, among others.