BACKGROUND:To explore correlation between the quality of surgery and outcome in high-risk soft tissue sarcoma (STS) patients treated within a phase III randomized trial. PATIENTS AND METHODS:In the trial, all patients received three cycles of preoperative chemotherapy (CT) with epirubicin 120 mg/m(2) and ifosfamide 9 g/m(2) and were randomly assigned to receive two further postoperative cycles. Radiotherapy (RT) could be delivered in the preoperative or postoperative setting. The association between surgical margins and overall survival (OS) was studied in a univariate and multivariate fashion. RESULTS:Two hundred and fifty-two patients completed the whole treatment and were operated conservatively. At a median follow-up of 60 months (IQR, 45-74 months), the 5-year OS was 0.73, even in patients with positive and negative margins. The 5-year cumulative incidence (CI) of local recurrence (LR) in patients with positive and negative microscopic margins was 0.17 (standard error, SE, 0.08) and 0.03 (SE, 0.01), respectively. In the subgroup of patients receiving combined preoperative CT-RT and with positive surgical margins, the CI of LR was 0. CONCLUSIONS:In this setting of high-risk STS treated by preoperative CT or CT-RT, the negative impact of positive margins on the outcome was limited. When close margins can be anticipated preoperative CT-RT may be a reasonable option to maximize the chance of cure.