• Dario Callegaro, Chandrajit P Raut, Taiwo Ajayi, Dirk Strauss, Sylvie Bonvalot, Deanna Ng, Eberhard Stoeckle, Mark Fairweather, Piotr Rutkowski, Winan J van Houdt, Hans Gelderblom, Claudia Sangalli, Andrew Hayes, Charles Honoré, Rebecca A Gladdy, Magali Fau, Rick Haas, Dimitri Tzanis, Aisha B Miah, Peter Chung, Elizabeth H Baldini, Sandrine Marreaud, Saskia Litiere, Carol J Swallow, and Alessandro Gronchi.
• Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
• Ann. Surg. 2023 Jul 1; 278 (1): 127134127-134.

ObjectiveThe aim of the present study was to compare the effect of radiotherapy (RT) on abdominal recurrence-free survival (ARFS) in patients with primary retroperitoneal sarcoma treated in the EORTC-STBSG-62092 (STRASS) phase 3 randomized controlled trial (STRASS cohort) and off-trial (STREXIT cohort) and to pool STRASS and STREXIT data to test the hypothesis that RT improves ARFS in patients with liposarcoma.BackgroundThe STRASS trial did not show any difference in ARFS between patients treated with preoperative radiotherapy+surgery (RT+S) versus surgery alone (S).MethodsAll consecutive adult patients not enrolled in STRASS and underwent curative-intent surgery for a primary retroperitoneal sarcoma with or without preoperative RT between 2012 and 2017 (STRASS recruiting period) among ten STRASS-recruiting centres formed the STREXIT cohort. The effect of RT in STREXIT was explored with a propensity score (PS)-matching analysis. Primary endpoint was ARFS defined as macroscopically incomplete resection or abdominal recurrence or death of any cause, whichever occurred first.ResultsSTRASS included 266 patients, STREXIT included 831 patients (727 after excluding patients who received preoperative chemotherapy, 202 after 1:1 PS-matching). The effect of RT on ARFS in STRASS and 1:1 PS-matched STREXIT cohorts, overall and in patients with liposarcoma, was similar. In the pooled cohort analysis, RT administration was associated with better ARFS in patients with liposarcoma [N=321, hazard ratio (HR), 0.61; 95% confidence interval (CI), 0.42-0.89]. In particular, patients with well-differentiated liposarcoma and G1-2 dedifferentiated liposarcoma (G1-2 DDLPS, n=266) treated with RT+S had better ARFS (HR, 0.63; 95% CI, 0.40-0.97) while patients with G3 DDLPS and leiomyosarcoma had not. At the current follow-up, there was no association between RT and overall survival or distant metastases-free survival.ConclusionsIn this study, preoperative RT was associated with better ARFS in patients with primary well-differentiated liposarcoma and G1-2 DDLPS.Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.

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