Primary vaginal cancer treated with high-dose rate brachytherapy and intraprocedural magnetic resonance imaging.

Abstract

Purpose: To report outcomes among primary vaginal cancer patients treated definitively with either external beam radiation therapy plus high-dose rate (HDR) brachytherapy (EBRT-BT) or BT (BT) alone with placement of interstitial catheters under magnetic resonance imaging (MRI) guidance.

Methods: Retrospective review of 41 patients treated for primary vaginal cancer from 2016 to 2022. Kaplan-Meier (KM) estimates were generated for disease-free survival (DFS), local control (LC), and overall survival (OS).

Results: Median follow-up was 28 months (range 2-82 months). A total of 36 patients had EBRT-BT, 5 had BT alone. Forty patients had template interstitial and 1 had a multichannel cylinder. Among patients who received EBRT-BT, median total D90 EQD2 was 68.3 Gray (Gy) (range 56.6-91.5 Gy); BT only, median 40.3 Gy (range 38.1-86.3 Gy). No patient experienced local only failure. Relapse occurred in 12 patients treated with EBRT-BT versus 1 with BT alone group. For the EBRT-BT cohort versus BT only cohort, 2-year OS was 81% versus 60%, DFS 61% versus 40%, and LC was 94% versus 80%, respectively. For the entire cohort, 2-year OS was 67%, and median OS was 5 years. The 2-year DFS was 57% and 2-year LC was 93%. The most common any grade acute treatment-related toxicity were grade 1 vaginal pain and stenosis. Grade 3 acute and late toxicities were minimal.

Conclusions: MRI-guided HDR BT for primary vaginal cancer yields high rates of local control with limited toxicities. Lower rates of distant control indicate the need for newer options such as immunotherapy or other systemic agents.