Résumé
Objectives. We aim to report the outcomes of soft tissue sarcoma (STS) patients with surgical R0 margin size (large: ≥5 mm or close: ≥1 to <5 mm) tumour, treated or not with postoperative radiotherapy (RT). Methods. The Connective Tissue Cancer Network database CONTICABASE collected data from adult patients diagnosed from 1999 to 2016 for histologically-proven locally advanced STS of trunk or limbs, with surgical R0 margin size (large: ≥5 mm; close: ≥1 to <5 mm), who did not receive neoadjuvant/adjuvant chemotherapy. A propensity score matching analysis was performed to account for potential treatment selection biases. We reported local control (LC), disease-free survival (DFS), overall survival (OS), RT impact in subgroup analyses, and performed multivariable analyses adjusted for classical prognostic factors. Results Among 738 patients with STS eligible from 11 sites, 524 patients had R0 surgical margins, either treated with postoperative RT (N = 374, 71.4%), or not (N = 150). Besides similar characteristics regarding sex, age, margin size, and preoperative MRI assessment, more tumour localizations in lower limbs (62.8% vs 46%), larger tumours (≥5 cm) (68.4% vs 46%), deeper tumours (75.9% vs 56%), and more grade ≥3 tumours (50.4% vs 32.7%) were reported in patients having received adjuvant RT. The median follow-up was 74.7 [95% CI 71.8-83.0] months, 10-year-LC, -DFS, and -OS were 77.5% [95% CI 71.2-82.6], 51.0% [45.1-56.7], and 69.6% [63.7-74.6], respectively. The multivariable analysis showed that patients with older age and larger tumours are more at risk in terms of LC, DFS, and OS. Preoperative MRI assessment (HR 0.43, 95% CI 0.22-0.83; P = .012) and RT (HR 0.27, 95% CI 0.15-0.49; P < .001) were significantly associated with better LC. However, RT did not impact OS. Subgroup analyses showed that RT also benefit to grade 1 and 2 tumours. Conclusion. This series shows that adjuvant RT improved LC in all patients with STS with surgical R0 resection. Advances in knowledge This series did not identify subgroups in whom RT can be deleted.