Low-dose adjuvant vaginal cylinder brachytherapy for early-stage non-endometrioid endometrial cancer: recurrence risk and survival outcomes

Abstract

Objective: The aim of this study was to evaluate recurrence patterns and survival outcomes for patients with early-stage non-endometrioid endometrial adenocarcinoma treated with adjuvant high-dose rate vaginal brachytherapy with a low-dose scheme.

Methods: A retrospective review was performed of patients with International Federation of Gynecology and Obstetrics (FIGO) stage I-II non-endometrioid endometrial cancer who received adjuvant vaginal brachytherapy with a low-dose regimen of 24 Gy in six fractions from November 2005 to May 2017. All patients had >6 months of follow-up. Rates of recurrence-free survival, overall survival, vaginal, pelvic, and distant recurrence were calculated by the Kaplan-Meier method. Prognostic factors for recurrence and survival were evaluated by Cox proportional hazards modeling.

Results: A total of 106 patients were analyzed. Median follow-up was 49 months (range 9-119). Histologic subtypes were serous (47%, n=50), clear cell (10%, n=11), mixed (27%, n=29), and carcinosarcoma (15%, n=16). Most patients (79%) had stage IA disease, 94% had surgical nodal assessment, and 13% had lymphovascular invasion. Adjuvant chemotherapy was delivered to 75%. The 5-year recurrence-free and overall survival rates were 74% and 83%, respectively. By histology, 5-year recurrence-free/overall survival rates were: serous 73%/78%, clear cell 68%/88%, mixed 88%/100%, and carcinosarcoma 56%/60% (p=0.046 and p<0.01). On multivariate analysis, lymphovascular invasion was significantly associated with recurrence (HR 3.3, p<0.01). The 5-year vaginal, pelvic, and distant recurrence rates were 7%, 8%, and 21%, respectively. Vaginal and pelvic recurrence rates were highest for patients with carcinosarcoma, lymphovascular invasion and/or FIGO stage IB/II disease. At 5 years, vaginal and pelvic recurrence rates for patients with lymphovascular invasion were 33% and 40%, respectively. Patients with stage IA disease or no lymphovascular invasion had 5-year vaginal recurrence rates of 4% and pelvic recurrence rates of 6% and 3%, respectively.

Conclusions: Adjuvant high-dose rate brachytherapy with a low-dose scheme is effective for most patients with early-stage non-endometrioid endometrial cancer, particularly stage IA disease and no lymphovascular invasion. Pelvic radiation therapy should be considered for those with carcinosarcoma, lymphovascular invasion and/or stage IB/II disease.

Keywords: endometrial neoplasms; endometrium; radiation oncology; radiotherapy dosage.