EROS study: evaluation between high-dose-rate and low-dose-rate vaginal interventional radiotherapy (brachytherapy) in terms of overall survival and rate of stenosis

Purpose
To compare the survival and toxicity outcomes in patients with endometrial cancer treated with either high-dose-rate (HDR) or low-dose-rate (LDR) vaginal brachytherapy (VBT) following external beam radiotherapy (EBRT).

Material and methods
From January 2000 to December 2014, patients with endometrial cancer after radical hysterectomy with/without pelvic and/or para-aortic lymphadenectomy were treated with adjuvant EBRT (45 Gy, 1.8 Gy/day to the whole pelvis) and subsequent VBT boost (HDR dose of 7 Gy in one fraction or LDR VBT dose of 25 Gy). The dose was prescribed at 0.5 cm from the surface of the applicator and the proximal half to two-thirds of the vagina was irradiated. The outcomes of patients were evaluated in terms of local control (LC), overall survival (OS), and rates of adverse events.

Results
We analyzed data of 200 patients treated with EBRT followed by HDR VBT boost in 78 patients and LDR VBT boost in 122 patients. With a median follow-up of 25 months (range, 6-163), 5-year OS was 98% and 97% in the LDR and HDR groups, respectively (p = 0.37). The 5-year LC was similar (93% in both groups) (p = 0.81). In multivariate analyses, none of the factors assessed (age, stage, grade) impacted OS (p = 0.37) or LC (p = 0.81). Patients treated with LDR VBT after EBRT had higher rates of acute gastrointestinal toxicity. No differences were found in acute genitourinary or hematological toxicities. Late toxicity such as vaginal stenosis was registered during regular follow-up visits and was similar in the two groups (p = 0.67).

Conclusions
In our analysis, there were no differences in terms of OS and late toxicity outcomes for patients receiving LDR or HDR VBT. HDR VBT is a safe technique in comparison to LDR VBT.