Abstract Objectives The optimal approach in the management of endometrial stromal sarcoma (ESS) remains unclear. The aim of the present study was to retrospectively report the outcome of patients treated for ESS in our hospital over a 27-year period in order to evaluate the treatment results and the role of radiotherapy. Patients and methods From 1979 to 2006, 13 patients with ESS were treated at the Hospital Clínic of Barcelona. Pa- tients underwent abdominal hysterectomy and bilateral salpingo-oophorectomy. The 1989 FIGO classification for endometrial carcinoma was used in this retrospective study. Seven patients presented stage I (6 IB and 1 IC), 1 stage II, 3 stage III and 2 stage IV. Nine patients had high-grade tumours with an infiltration of the outer 50% of the myo- metrium. Postoperative radiotherapy was administered in 10 patients. Results The mean follow-up of the patients was 54.6 months (range between 3 and 190). Patients with stage IB had a better outcome in comparison to more advanced stag- es. Five of the six patients with stage IB received adjuvant radiotherapy and none developed local recurrence, while one patient who received no treatment with radiotherapy had a relapse. Seven of the 13 patients had stages over IB: 5 who had received radiotherapy after surgery had lo- coregional control and 2 who did not receive radiotherapy had local relapse. Nine patients had high-grade tumours, 6 received radiotherapy after surgery and only one had lo- cal relapse. Of the three who did not receive radiotherapy, 2 relapsed locally. Local control rate of the patients who received adjuvant radiotherapy was higher than in the pa- tients who did not (88.9% vs. 50%). Conclusions Our data reveal that deep myometrial invasion and stage over IB are significantly associated with poor overall survival and this finding is similar to those of stud- ies in patients with endometrial cancer. The present study showed that the local control was higher in patients receiv- ing radiotherapy. Keywords Uterine endometrial stromal sarcomas · Radiotherapy Introduction Endometrial stromal sarcoma (ESS) is a very rare entity of uterine malignancy, accounting for 0.2–1% of all uterine malignancies and representing about 10% (range 6–20%) of all uterine sarcomas [1]. ESSs were defined by Norris and Taylor as tumours composed of cells closely resem- bling those of endometrial stroma. ESSs have traditionally I. Valduvieco () · Á. Rovirosa · A. Biete Radiation Oncology Department Hospital Clínic i Universitari C/ Villarroel, 170 ES-08036 Barcelona, Spain e-mail: ivalduvi@clinic.ub.es Á. Rovirosa · A. Biete IDIBAPS Barcelona, Spain Ll. Colomo Pathology Department Hospital Clínic i Univesitari Barcelona, Spain A. de San Juan Gynaecologic and Obstetrics Department Hospital de Mollet Barcelona, Spain J. Pahisa Gynaecologic and Obstetrics Department Hospital Clínic i Universitari Barcelona, Spain Clin Transl Oncol (2010) 12:226-230 DOI 10.1007/s12094-010-0493-9 RESEARCH ARTICLES Endometrial stromal sarcoma. Is there a place for radiotherapy? Izaskun Valduvieco · Ángeles Rovirosa · Lluis Colomo · Alex De San Juan · Jaume Pahisa · Albert Biete Received: 24 August 2009 / Accepted: 2 January 2010