Postoperative endometrial cancer treatments with electronic brachytherapy source

Purpose This study is a dosimetric and acute toxicity comparison of endometrial cancer patients treated with either Axxent (Xoft, Inc., San José, CA, USA) electronic and interstitial brachytherapy versus interstitial high dose rate brachytherapy (HDRBT). Materials and Methods Between 2015 and 2017, 94 patients with postoperative endometrial cancer were treated in our centre with the Axxent electronic brachytherapy (eBT) system. The V 150 and V 200 are evaluated prospectively for each plan. The mean age of patients was 65.9 years (age range 33-84 years), with different tumour staging. Of the 94 patients, 37 received exclusive adjuvant brachytherapy (25 Gy in five sessions); the remaining patients received external beam radiotherapy (EBRT) with a regimen of 23 sessions of 2 Gy each to the entire pelvis, followed by eBT (15 Gy in three sessions). Additionally, the absorbed doses received by the organs at risk (OAR), urinary bladder, rectum and sigmoid colon were compared with HDRBT plans, evaluating D 2cc, V 50% and V 35%. Median follow-up was done for each of the 94 patients to assess the toxicity of the treatment: vaginal mucosa toxicity, rectal and urinary toxicity; and results are presented for acute toxicity, toxicity at 1 month after the end of treatment and follow-up after 12 months for a portion of patients according to the Radiation Therapy Oncology Group (RTOG) toxicity criteria. Results The doses in OAR for eBT plans were lower than that for HDRBT plans, both Ir-192 and Co-60 plans, whose doses were similar. The dose in bladder with eBT was 63.8% of the prescribed dose for D 2cc versus 70.1% for HDRBT Ir-192, for V 50% was 7.2% versus 12.7% and for V 35% was 15.2% versus 28.2%. In rectum the D 2cc was 61.2% versus 68.4%, for V 50% was 7.9% versus 14.3% and for V 35% was 16.7% versus 32%. Results demonstrated lower doses to OAR in all eBT plans. Acute toxicity in eBT was very low in cases of mucositis, with only one case of toxicity greater than grade 1, rectal toxicity and urinary toxicity; results at 1 month are equally good, toxicity symptoms disappeared and no relapses have occurred to date. Conclusions The results of treatment with the Axxent eBT unit for 94 patients are very good, as no recurrence has been observed and the toxicity of the treatment is very low. The increase in V 150 and V 200 has not produced an increase in vaginal mucosa toxicity, and the doses in the OAR are lower than in the plans implemented for HDRBT with Ir-192 or Co-60. eBT is a good alternative to treat endometrial cancer in centres without conventional HDR availability. To date, there are limited published studies reporting on outcomes from patients treated with eBT

Adjuvant Electronic Brachytherapy For Patients With Endometrial Cancer

Purpose/Objective(s) Brachytherapy plays a fundamental role in the adjuvant treatment of endometrial cancer (EC) to decrease vaginal cuff recurrence. Traditionally high dose rate (HDR) brachytherapy with Iridium 192 (Ir-192) had been used, but the recent development of electronic brachytherapy (eBT) based on X-ray emissions could be an alternative. Our objectives are to analyze the local recurrence in EC treated with eBT, toxicity profile and to compare with series from the literature with HDR Ir-192 brachytherapy. Materials/Methods From September 2015 to January 2019, 271 patients with endometrial cancer were treated with vaginal eBT at our institution. 117 patients received vaginal eBT as monotherapy and 154 as a boost after external beam radiation therapy (EBRT). We used different dose-fractionation schedules: total dose was 15 Gy in 3 fractions or 14 Gy in 2 for eBT as a boost to EBRT; and 25 Gy in 5 fractions or 21 Gy in 3 fractions for exclusive eBT. Acute and late toxicities were recorded using Common Terminology Criteria for Adverse Events (CTCAE) v4.0. Data was collected retrospectively. Results The median follow-up was 24 months. The average age was 66 years. 70% were diagnosed as endometrioid carcinoma (Type I). According to the International Federation of Gynaecology and Obstetrics (FIGO) classification: 30% FIGO IA; 39% FIGO IB and 31% FIGO =IIA. Acute toxicity: 33% had vaginal toxicity; 10% had urinary toxicity; 8% had rectal toxicity and all of them were =Grade 1 (G1) or G2. G1-G2 chronic toxicity was observed: 10% vaginal toxicity; 1% urinary toxicity; 8% rectal toxicity; 3 patients (1.5%) had G3 rectal late toxicity. A statistically significant difference was found in the rectal toxicity observed at the patients treated with EBRT plus eBT versus eBT as monotherapy (p = 0.008). 8 patients had locoregional recurrence, 8 had systemic recurrence and 12 had both recurrences. Only 1 vaginal cuff relapse was observed. Our series, shows an increase in acute G1 vaginal mucosa toxicity with respect to HDR Ir-192 brachytherapy (33% vs 15.8%), but reduction of late vaginal mucosal toxicity (10% eBT vs. 23% Ir-192). Vaginal cuff recurrence results were better than the literature (0.36% eBT vs. 0.7-1.4% Ir-192). Conclusion eBT at endometrial cancer is a feasible alternative to HDR brachytherapy with Ir-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 reduction in the dose of organs at risk, benefits for staff and health system as mobility, versatility and ease of installation of the equipment. Further research is needed to establish eBT as an alternative to high dose rate brachytherapy