Outcomes and toxicity after salvage radiotherapy for vaginal relapse of endometrial cancer

Objectives Studies of salvage radiotherapy in locally recurrent endometrial cancer remain limited. The aim of this study was to evaluate the efficacy of salvage radiotherapy for vaginal relapse of endometrial cancer and to explore prognostic factors associated with outcomes. Methods We evaluated 30 patients treated with salvage external-beam radiotherapy and/or vaginal brachytherapy for vaginal relapses of endometrial cancer between 2009 and 2018. The inclusion criteria were: pathologically-confirmed recurrence; loco-regional relapse (in absence of distant metastases); and salvage treatment including external-beam radiotherapy and/or vaginal brachytherapy. Outcomes were evaluated via Kaplan-Meier, with the log-rank test employed to compare differences among various groups and identify prognostic factors. Results 30 patients developed vaginal recurrence at a median time of 20.6 months (range 2—219) post-hysterectomy. The most common site of recurrence was the vaginal apex (60%), followed by the distal vagina (10%). Salvage radiotherapy entailed combination external-beam radiotherapy and vaginal brachytherapy (n=24) or single modality treatment (n=6), along with concurrent chemotherapy in 20 cases. At a median follow-up of 4.4 years (range 0.1–130) post-radiotherapy, the 5 year rates of local control, regional control, metastasis-free interval, disease-free interval, and overall survival were 89%, 91.5%, 75.5%, 69%, and 83%, respectively. Factors associated with improved disease-free interval included: endometrioid histology (p=0.03), isolated vaginal relapse (p=0.003), late recurrence (>9 months) (p=0.007), and combined modality radiotherapy (p=0.001). The only factor associated with overall survival was isolated vaginal relapse (in the absence of other recurrent disease) (p=0.02). Regarding toxicity, 18% of patients experienced acute grade ≥3 events (most commonly gastrointestinal). The 5 year rates of rectal bleeding, small bowel obstruction, and pelvic fracture were 31%, 18%, and 13%, respectively. Conclusions Salvage radiotherapy imparts excellent loco-regional control for vaginal relapses of endometrial cancer and should entail combination external-beam radiotherapy and vaginal brachytherapy. Patients should be closely monitored for late gastrointestinal toxicity following salvage radiotherapy.