Image-Guided Adaptive Brachytherapy (IGABT) for Primary Vaginal Cancer: Results of the International Multicenter RetroEMBRAVE Cohort Study

Simple Summary Primary vaginal cancer is a rare disease and, consequently, evidence about the outcome of treatment is scarce. The aim of our retrospective, observational multicenter study was to assess the oncological outcome of the nowadays standing treatment for vaginal cancer, namely radio(chemo)therapy, followed by image-guided adaptive brachytherapy (IGABT). Our study confirms the results of the earlier published small monocentric IGABT studies, showing a high local control with acceptable morbidity. Notably, patients with large (T3/T4) tumors especially seem to benefit from volumetric (3D) image-guided brachytherapy, as compared to two-dimensional-based radiotherapy. In addition, although interpreted with caution, as for cervical cancer, a higher dose seems to lead to better local control. These results should, however, be further investigated in a prospective trial. Purpose: This study assessed outcomes following the nowadays standing treatment for primary vaginal cancer with radio(chemo)therapy and image-guided adaptive brachytherapy (IGABT) in a multicenter patient cohort. Methods: Patients treated with computer tomography (CT)-MRI-assisted-based IGABT were included. Retrospective data collection included patient, tumor and treatment characteristics. Late morbidity was assessed by using the CTCAE 3.0 scale. Results: Five European centers included 148 consecutive patients, with a median age of 63 years. At a median follow-up of 29 months (IQR 25-57), two- and five-year local control were 86% and 83%; disease-free survival (DFS) was 73% and 66%, and overall survival (OS) was 79% and 68%, respectively. Crude incidences of >= grade-three urogenital, gastro-intestinal and vaginal morbidity was 8%, 3% and 8%, respectively. Lymph node metastasis was an independent prognostic factor for disease-free survival (DFS). Univariate analysis showed improved local control in patients with T2-T4 tumors if >80 Gy EQD2(alpha/beta 10) was delivered to the clinical target volume (CTV) at the time of brachytherapy. Conclusions: In this large retrospective multicenter study, IGABT for primary vaginal cancer resulted in a high local control with acceptable morbidity. These results compared favorably with two-dimensional (2D) radiograph-based brachytherapy and illustrate that IGABT plays an important role in the treatment of vaginal cancer.