Image-Guided High-Dose-Rate Brachytherapy for Definitive Management of Primary Vaginal Cancer: A Single Institutional Experience.

PURPOSE/OBJECTIVE(S): To assess the safety and efficacy of image-guided high-dose-rate brachytherapy (IGBT) alone or in combination with external beam radiation therapy (EBRT) for the treatment of vaginal cancers.

MATERIALS/METHODS: The study analyzed patients diagnosed with primary vaginal cancers from 2004 to 2021 who received definitive radiotherapy at a single institution. Interstitial implants were performed using a freehand technique and transvaginal or transrectal-ultrasound for imaging guidance. IGBT was planned using inverse planning simulated annealing (IPSA) software. Data collected and analyzed included patient and tumor characteristics, dose and fractionation, and treatment outcomes. Complications were assessed using CTCAEv4 scores, and descriptive and survival analyses were performed using R-studio.

RESULTS: Sixty-six patients met inclusion criteria. Patients were staged as I (14), II (23), III (19), and IV (10) based on revised FIGO 2018 staging. 47 (72%) had squamous cell carcinoma histology, and median age was 65 years. The most common regimen was 45 Gy in 25 fractions of EBRT followed by IGBT boost of 18 Gy in 3 fractions with 1 implant (n = 40). For melanoma, an IGBT boost of 19 Gy in 2 fractions with a single implant was used (n = 7). For IGBT monotherapy, the most common regimen was 36 Gy in 6 fractions delivered over 2 implants (n = 3). 41 (66%) of the patients received systemic therapy. Local failures occurred in 8 (12%) patients, while 8 (12%) developed distant metastases. Median overall survival was 64.7 months. Overall survival was 64.3% (95% CI 51.9-79.7%) at 3 years, and 50.9% (95% CI 35.7-72.5%) at 5 years. Grade 3 or 4 toxicities were reported in 4 (6%) patients including vaginal fistula (n = 3) and urethral stricture (n = 1).

CONCLUSION: The results suggest that utilizing IGBT for freehand interstitial implants in combination with EBRT is a safe and effective primary treatment for vaginal cancer, with durable local control and low toxicity. Further research is needed to establish multi-institutional practice patterns and recommendations.