90th Annual Meeting Abstracts
Surgery and Radiation Therapy for Abdominal and Retroperitoneal Sarcoma: Both Necessary and Sufficient?
*Zheng Zhou, MD, PhD, *Theodore P McDade, MD, *Jessica P Simons, MD, *Sing Chau Ng, MS, *Laura A Lambert, MD, Giles F Whalen, MD, *Shimul A Shah, MD, Jennifer F Tseng, MD, MPH
University of Massachusetts Medical School, Worcester, MA
Objective: While surgery and radiotherapy (RT) are utilized for abdominal and retroperitoneal soft tissue sarcomas, their impact on survival on a national level is not well-defined. This study aimed to evaluate the effect of surgical resection and RT on survival in U.S. patients with retroperitoneal/abdominal sarcoma.
Design: Retrospective cohort.
Setting: Surveillance Epidemiology and End Results, 1988-2005
Patients: Among adults, 2733 cases of retroperitoneal and peritoneal soft tissue sarcomas were identified; 1901 cases had locoregional disease.
Main Outcome Measures: Survival in the first two years after diagnosis. Kaplan-Meier survival analysis stratified based on surgery and RT status. Cox proportional hazards model was used to assess the adjusted effect of surgery and RT.
Results: Survival was significantly different between the groups with locoregional versus distant disease (log rank, p<0.0001). Of 1901 patients with locoregional disease, 83% underwent resection, and 24% received RT. Adjusted Cox regression analysis of locoregional patients demonstrated both resection (HR 0.26, 0.20-0.33, p<0.0001) and RT (hazard ratio (HR) 0.73, 0.55-0.96, p=0.0219) were independent predictors of survival. Among AJCC stage I patients (n=681), RT remained predictive of survival (HR 0.47, 0.24-0.92, p=0.0266) independent of the benefit from resection (HR 0.34, 0.21-0.56, p<0.0001). For AJCC stage II-III patients (n=543), surgical resection remained protective (HR 0.23, 0.17-0.31, p<0.0001), but not RT (HR 0.82, 0.61-1.11, p=0.2091).
Conclusions: In a large national cohort of abdominal and retroperitoneal sarcomas, surgical resection was associated with an independent survival advantage that persisted across all stages. Radiotherapy provided an additional benefit for patients with AJCC Stage I disease. These results suggest that resection should be offered to all reasonable surgical candidates; radiotherapy may most benefit those operable patients with earlier-stage disease.