PurposeTo investigate the clinical feasibility and treatment outcomes of image-based high dose rate (HDR) brachytherapy using an intracavitary multichannel vaginal cylinder for the definitive treatment of vaginal cancersMaterials and MethodsForty-one patients with vaginal cancer (24% primary vaginal, 76% recurrence from other gynecologic primaries) treated with definitive radiotherapy ± chemotherapy including image-based HDR brachytherapy with a multichannel vaginal cylinder. Image-based brachytherapy was completed using either CT-based (41%) or MR-based planning (59%) with each fraction. The high-risk clinical target volume (HR-CTV) was defined based on the pre- and post-external beam radiotherapy GTV (see Figure). Doses were converted to equivalent dose of 2Gy per fraction (EQD2Gy). Endpoints examined: dose-volume parameters and early clinical outcomes.ResultsThe median HR-CTV volume was 24.2cc [Interquartile range (IQR): 12.6], with a median dose to 90% (D90) of 77.1Gy (IQR: 3.4). The median dose to 2cc (D2cc) for the bladder, rectum, and sigmoid were 59.4Gy (IQR: 5.6), 58.2Gy (IQR: 4.1), and 52.3Gy (IQR: 5.5) respectively. After a median follow-up of 16 months (range: 3-35), complete clinical response was documented in 98% of patients. The 2-year local control, regional control, distant control, disease free survival and overall survival were 93%, 100%, 81%, 78% and 88%. The 2-year actuarial rate of late ≥ grade 3 toxicity was 4% overall with 0% vaginal, 0% bladder, urethral 0%, and 4% gastrointestinal, respectively.Conclusions PurposeTo investigate the clinical feasibility and treatment outcomes of image-based high dose rate (HDR) brachytherapy using an intracavitary multichannel vaginal cylinder for the definitive treatment of vaginal cancers To investigate the clinical feasibility and treatment outcomes of image-based high dose rate (HDR) brachytherapy using an intracavitary multichannel vaginal cylinder for the definitive treatment of vaginal cancers Materials and MethodsForty-one patients with vaginal cancer (24% primary vaginal, 76% recurrence from other gynecologic primaries) treated with definitive radiotherapy ± chemotherapy including image-based HDR brachytherapy with a multichannel vaginal cylinder. Image-based brachytherapy was completed using either CT-based (41%) or MR-based planning (59%) with each fraction. The high-risk clinical target volume (HR-CTV) was defined based on the pre- and post-external beam radiotherapy GTV (see Figure). Doses were converted to equivalent dose of 2Gy per fraction (EQD2Gy). Endpoints examined: dose-volume parameters and early clinical outcomes. Forty-one patients with vaginal cancer (24% primary vaginal, 76% recurrence from other gynecologic primaries) treated with definitive radiotherapy ± chemotherapy including image-based HDR brachytherapy with a multichannel vaginal cylinder. Image-based brachytherapy was completed using either CT-based (41%) or MR-based planning (59%) with each fraction. The high-risk clinical target volume (HR-CTV) was defined based on the pre- and post-external beam radiotherapy GTV (see Figure). Doses were converted to equivalent dose of 2Gy per fraction (EQD2Gy). Endpoints examined: dose-volume parameters and early clinical outcomes. ResultsThe median HR-CTV volume was 24.2cc [Interquartile range (IQR): 12.6], with a median dose to 90% (D90) of 77.1Gy (IQR: 3.4). The median dose to 2cc (D2cc) for the bladder, rectum, and sigmoid were 59.4Gy (IQR: 5.6), 58.2Gy (IQR: 4.1), and 52.3Gy (IQR: 5.5) respectively. After a median follow-up of 16 months (range: 3-35), complete clinical response was documented in 98% of patients. The 2-year local control, regional control, distant control, disease free survival and overall survival were 93%, 100%, 81%, 78% and 88%. The 2-year actuarial rate of late ≥ grade 3 toxicity was 4% overall with 0% vaginal, 0% bladder, urethral 0%, and 4% gastrointestinal, respectively. The median HR-CTV volume was 24.2cc [Interquartile range (IQR): 12.6], with a median dose to 90% (D90) of 77.1Gy (IQR: 3.4). The median dose to 2cc (D2cc) for the bladder, rectum, and sigmoid were 59.4Gy (IQR: 5.6), 58.2Gy (IQR: 4.1), and 52.3Gy (IQR: 5.5) respectively. After a median follow-up of 16 months (range: 3-35), complete clinical response was documented in 98% of patients. The 2-year local control, regional control, distant control, disease free survival and overall survival were 93%, 100%, 81%, 78% and 88%. The 2-year actuarial rate of late ≥ grade 3 toxicity was 4% overall with 0% vaginal, 0% bladder, urethral 0%, and 4% gastrointestinal, respectively. Conclusions