IMAGE-Guided Brachytherapy for Primary Vaginal Cancers

Abstract

To evaluate disease control and toxicities of primary vaginal cancer treated with image-guided brachytherapy. A retrospective study was performed on 26 consecutive patients treated for vaginal cancer with brachytherapy (BT) between 2010 and 2018, all treated after the introduction of ultrasound-based catheter guidance and modified dose optimization to reduce vaginal toxicities. External beam radiation therapy (EBRT) was used in 25/26 patients, with a median dose of 45 Gy in 25 fractions. 16/25 patients had concomitant chemotherapy with EBRT. Endocavitary BT alone was used in 3/26 patients. Interstitial BT was used in 23/26 patients. Standard procedure involved the use of a cylinder and interstitial catheters. They were usually inserted under Transrectal Ultrasound (TRUS) and/or TransVaginal Ultrasound (TVUS) guidance. Inverse Planning Simulated Annealing (IPSA) was used for dose optimization and a class solution was developed to reduce high-dose points in the vaginal mucosa by keeping most of the high dose inside the cylinder. Acute (<6 months) and late genitourinary (GU), gastrointestinal (GI), and vaginal toxicities were reported using the Common Terminology Criteria for Adverse Events version 5 (CTCAE v5). Local control (LC), metastatic disease-free survival (mDFS) and overall survival (OS) were evaluated using Kaplan-Meier survival curves. Mean age was 69,7 years old. Median follow-up was 35,5 months (range 0-85months). 18/26 patients had Squamous Cell Carcinoma (SCC), 5/26 Adenocarcinoma, 1/26 Clear Cell Carcinoma, 1/26 Melanoma and 1/26 Squamous Transitional Carcinoma. 13%, 71%, 8%, and 8% of patients had FIGO stages I, II, III, and IV respectively. LC of 83% and 83%, mDFS of 91 % and 91%, and OS of 80% and 66 %, were respectively achieved at 3 and 5 years. When limited to SCC only, LC of 88% and 88%, mDFS of 94 % and 94%, and OS of 87% and 70 %, were respectively achieved at 3 and 5 years. There were only 4 local relapses, which all occurred within 8 months after treatment. One was a stage IV SCC at diagnosis, one had a squamous transitional carcinoma, one was a clear cell carcinoma, and the last one had concomitant multiple distant metastasis at time of local relapse. There were no late G3-4 GU/GI toxicity. Acute and late G3 vaginal toxicity (stenosis) occurred in 19% and 42% of patients, respectively. 3 cases of vaginal necrosis and 1 suspicion of fistula were reported, all associated with a local progression of the disease except for one case where necrosis was limited and healed spontaneously. No patient needed Hyperbaric Oxygen Therapy (HBOT). Excellent local control can be achieved with the use of TRUS/TVUS-guided vaginal brachytherapy in primary vaginal cancer, especially for Squamous Cell Carcinoma, with a favorable toxicity profile. GU and GI toxicities are mild, but there is a significant number of G3 vaginal stenosis in this cohort of older patients. This might be reduced with the regular use of a vaginal dilator.