Outcomes of intermediate-risk to high-risk stage I endometrial cancer: 10-year clinical experiences of using in-house multi-channel applicators in a single center.

Background: There are only very few reports on clinical outcomes using multi-channel applicators (MCA) for patients with endometrial cancer (EC) in China. We aimed to evaluate the clinical experience of treating intermediate-risk (IR) to high-risk (HR) stage I EC using in-house made multi-channel applicators (IH-MCA) in a single institution.

Methods: Three hundred and ninety patients with stage I IR to HR EC were treated with hysterectomy and adjuvant radiotherapy from 2003 to 2015. All patients received post-operative vaginal cuff brachytherapy (VBT) alone or as a boost after external beam radiotherapy (EBRT). The prescriptions were 500 cGy per fraction for a total of 5 to 6 fractions with brachytherapy alone or 400 to 600 cGy per fraction for 2 to 3 fractions if it was combined with EBRT. Two types of applicators including a traditional rigid IH-MCA and a recent model custom-made with 3 dimension printing technology were used for treatment. The Kaplan-Meier method was used to calculate survival rate.

Results: Follow-up rate was 92.8% and the median follow-up time was 48 months (range 4-172 months). The 5-year overall survival (OS), progression-free survival, local recurrence, and distant metastasis rates for all patients were 96.3%, 92.1%, 2.9%, and 4.8% respectively. Two patients had isolated relapse in vagina outside the irradiated volume. The univariate and multivariate analysis showed that age and grade were the prognostic factors correlated with OS (hazard ratio: 0.368, 95% confidence interval [CI]: 0.131-1.035, P = 0.048; hazard ratio: 0.576, 95% CI: 0.347-0.958, P = 0.026,).

Conclusions: For patients with IR to HR stage I EC, adjuvant VBT alone or in combination with EBRT using IH-MCA led to excellent survival and recurrence rates. Age and grade were the prognostic factors correlated with OS.