Analysis of Adjuvant Vaginal Cylinder Brachytherapy for Endometrial Cancer: Recurrence Outcomes for Stage I and II Disease

Purpose: Treatment for primary endometrial cancer consists of total hysterectomy followed by adjuvant therapy for moderate risk disease. Vaginal cylinder brachytherapy is convenient, minimally toxic, and has been shown to reduce recurrence risk in the vagina. However, adjuvant treatment for Stage II disease is not well established. The purpose of our research is to examine patterns of recurrence following vaginal cylinder brachytherapy treatment for stage I and II endometrial cancer.

Methodology: Patients treated with vaginal cylinder brachytherapy between January 2011 and December 2018 were queried from a treatment database in a single academic department. A retrospective chart review was performed for Stage I and II patients. Patient age, dose of brachytherapy, adjuvant chemotherapy or external beam radiation use (yes/no), lymphovascular space invasion (LVSI) (yes/no), number of pelvic lymph nodes dissected, and site of recurrence (vagina, pelvis, or distant) were evaluated. A bivariate Cox regression analysis was performed to analyze factors associated with recurrence.

Results: Eighty-three patients received adjuvant cylinder brachytherapy for stage I or stage II endometrial cancer. Of these, 11 (13.2%) had stage IA disease, 35 patients (42.2%) had stage IB, and 37 patients (44.6%) had stage II. The majority of cases were grade 2 or 3 endometrioid histology: 54 (66.7%), and 18 (22.2%) cases respectively. Seven patients (8.6%) were more aggressive histologies (serous, clear cell). Only two patients (2.4%) had grade 1 disease. Thirty-one patients (37.4%) received adjuvant chemotherapy (due to high grade or aggressive histology) and seven (8.4%) received adjuvant external beam radiation. Sixty patients (72.3%) had a lymph node dissection with an average of 10.6 lymph nodes removed (standard deviation 10.5) with no nodes positive. Eighteen patients (22.0%) had LVSI. Median follow up was 2.9 years with interquartile range of 1.2 to 4.4 years. Nine patients (10.8%) had recurrence, with only two (2.4%) recurring in the vagina. For stage I patients, one recurred in the vagina, one recurred distantly, and three recurred distantly and in the pelvis. For stage II patients, one recurred in the vagina and three recurred distantly and in the pelvis. Stage II disease with negative pelvic nodes was not associated with significantly increased risk of recurrence relative to stage I disease (HR 1.03, CI (0.28 – 3.84)).

Conclusions: Vaginal recurrence rates after cylinder brachytherapy for Stage II patients with negative pelvic lymph nodes were low, similar to the low rate seen with Stage I disease. Most of the recurrences consisted of distant metastatic spread. A larger dataset including sufficient recurrences to support multivariate analysis is needed to identify independent factors associated with recurrence.

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