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Brachytherapy plays a fundamental role in the adjuvant treatment of endometrial cancer as almost every recurrence appears in the vaginal cuff. Traditionally HDR intracavitary brachytherapy with Iridium 192 had been used for this use, but the recent development of electronic brachytherapy based on X-ray emissions has important advantages over this one.  Our main objective has been to know the local control of electronic brachytherapy (EBT) in endometrial cancer, to know the toxicity profile and to compare with series from the literature with HDR IR-192 brachytherapy.

193 patients with endometrial cancer were retrospectively analyzed from September 2015 to May 2019 treated with electronic brachytherapy at the Miguel Servet University Hospital. The total dose was 15 Gy in 3 fractions or 14 Gy in 2 for brachytherapy complementary to external radiotherapy; and 25 Gy in 5 fractions or 21 Gy in 3 fractions for exclusive brachytherapy. Acute and late toxicities were recorded by CTCAE v 4.0 criteria.

The average age of the patients at diagnosis was 66.8 years and 74% diagnosed as endometrioid carcinoma (Type I). According to the FIGO classification, 38% were FIGO IB and the majority histopathological differentiation Grade was grade 2 with 40% observed. Some type of lymphadenectomy performed in 60% of the patients and 34% received adjuvant chemotherapy and 56% external radiotherapy. Mucosal toxicity was observed in 33.68% of the patients, urinary toxicity in 11.4% and rectal toxicity in 14%. All of them were Grade 1 toxicities except in 2 patients who presented Grade 2 acute mucosal toxicity (1%) and in 4 patients late complications Grade 3. Statistically significant association was found only with the rectal toxicity observed at the external beam radiotherapy treatment (p = 0.008). 13.5% of the patients (n=20) had locoregional recurrence and 20 patients distant recurrence. The median follow-up was 19 months and in that time, 15 patients died (8%). The results show an increase in acute grade 1 vaginal mucosal toxicity in our study respect  HDR Ir-192 brachytherapy (32% vs 15.8%), but with a decrease in acute grade 2 toxicity (1% EBT, 4.8% Ir-192) and almost absolute reduction of late vaginal mucosal toxicities (1% EBT, 23% Ir-192). The figures of vaginal vault recurrence and the death rate were concordant with the literature.

Electronic brachytherapy at endometrial cancer is a feasible alternative to HDR brachytherapy with Iridium 192 in effectiveness with an acceptable grade 1 acute toxicity. It has given long-term benefits for patients, providing the same dosimetric coverage in the area of ​​treatment as HDR brachytherapy with Iridium 192 with a marked reduction in the dose of organs at risk.