Impact of different adjuvant radiotherapy modalities on women with early-stage intermediate- to high-risk endometrial cancer

Abstract

Objective: Vaginal brachytherapy was recommended for patients with intermediate-risk endometrial cancer, however, optimal radiotherapy modalities for intermediate-high- or high-risk patients remains controversial. Previous studies have mainly focused on survival outcomes and have seldom taken cost issues into consideration, especially for high-risk patients. The purpose of this study is to compare the survival outcomes and costs associated with two adjuvant radiotherapy modalities in the management of patients with early-stage, intermediate- to high-risk endometrial cancer.

Methods: According to ESMO-ESCO-ESTRO criteria, 238 patients with stage I/II, intermediate- to high-risk endometrial cancer who underwent radiotherapy from January 2003 to December 2015 at our institution were reviewed. The vaginal brachytherapy group and external beam radiation therapy combined with the vaginal brachytherapy group were propensity score-matched at a 1:1 ratio. The Kaplan-Meier method and Cox proportional hazards regression model were used.

Results: A total of 361 patients met our inclusion criteria, the median age of the patients was 58 years (range, 28-85). All were diagnosed with stage I-II endometrial cancer (324 with stage I and 37 with stage II; 350 with endometrioid adenocarcinoma; and 10 with mucinous carcinoma). The median follow-up time was 60.5 months (range, 3-177). Among 119 matched pairs, no significant differences were found in overall (10.9% vs 8.4%, P=0.51), locoregional (4.2% vs 1.7%, P=0.45), or distant recurrence rates (6.7% vs 6.7%, P=1.0) between the two groups. There were also no differences in the 5-year overall (94.8% vs 93.9%, P=0.78) or progression-free survival (90.0% vs 84.4%, P=0.23) between the two groups. The rates of acute and late toxicity were significantly higher in the external beam radiation therapy combined with vaginal brachytherapy vs the vaginal brachytherapy group (all P<0.05), except for the acute hematological toxicity rate (17.6% vs 9.2%, P=0.06). External beam radiation therapy combined with vaginal brachytherapy had a higher median cost ($2759 vs $937, P<0.001) and longer median radiotherapy duration (41 days vs 17 days, P<0.001) than vaginal brachytherapy.

Conclusion: Vaginal brachytherapy was associated with similar local control and long-term survival outcomes relative to the combination of external beam radiotherapy and vaginal brachytherapy and it also minimizes radiation-related complications, reduces medical costs, and shortens radiotherapy duration. Vaginal brachytherapy may be the optimal radiation modality for patients with early-stage endometrial cancer at intermediate to high risk.

Keywords: brachytherapy; endometrial cancer; external beam radiation therapy; postoperative radiotherapy; propensity score matching.