Background: Evolving evidence suggests that, in selected patients with tumour category 1 (Tl) extremity soft tissue sarcoma (ESTS), surgery alone offers satisfactory results without decreasing survival. This study assessed the effect of sarcoma treatments on survival outcomes of Tl ESTS in a population-based data set. Methods: Using the Surveillance, Epidemiology, and End Results database, 1618 patients with primary ESTS underwent limb-sparing surgery. Multivariable analysis was used to assess the impact of radiotherapy on overall survival (OS) and sarcoma-specific survival (SSS), adjusting for co-variables. Results: Some 803 patients (49-6 per cent) underwent surgery alone for Tl ESTS. Radiotherapy in patients with low- and high-grade tumours did not result in any significant difference in OS or SSS. When stratified by grade, multivariable analysis showed that adjuvant radiotherapy was not an independent predictor of SSS (hazard ratio (HR) 1-05; P = 0-906) or OS (HR 0-89; P = 0-695) in lowgrade tumours. Neither was radiotherapy a .significant predictor of SSS (HR 0-87; P = 0-608) or OS (HR 0-67; P = 0-071) in high-grade tumours. Conclusion: This population-based appraisal validated previous evidence supporting a role for surgery alone in the treatment of Tl ESTS. Future policies should be tailored to offer patients minimal yet effective therapy, rather than maximum tolerated therapy.