Gynecologic oncology 2018-08
Image-based multichannel vaginal cylinder brachytherapy for the definitive treatment of gynecologic malignancies in the vagina.
Abstract
Purpose
Brachytherapy is integral to vaginal cancer treatment and is typically delivered using an intracavitary single-channel vaginal cylinder (SCVC) or an interstitial brachytherapy (ISBT) applicator. Multi-channel vaginal cylinder (MCVC) applicators allow for improved organ-at-risk (OAR) sparing compared to SCVC while maintaining target coverage. We present clinical outcomes of patients treated with image-based high dose-rate (HDR) brachytherapy using a MCVC.
Methods and materials
Sixty patients with vaginal cancer (27% primary vaginal and 73% recurrence from other primaries) were treated with combination external beam radiotherapy (EBRT) and image-based HDR brachytherapy utilizing a MCVC if residual disease thickness was 7 mm or less after EBRT. All pts received 3D image-based BT to a total equivalent dose of 70-80 Gy.
Results
The median high-risk clinical target volume was 24.4 cm3 (interquartile range [IQR], 14.1), with a median dose to 90% of 77.2 Gy (IQR, 2.8). After a median follow-up of 45 months (range, 11-78), the 4-year local-regional control, distant control, DFS, and OS rates were 92.6%, 76.1%, 64.0%, and 67.2%, respectively. The 4-year LRC rates were similar between the primary vaginal (92%) and recurrent (93%) groups (p = 0.290). Pts with lymph node positive disease had a lower rate of distant control at 4 years (22.7% vs. 89.0%, p < 0.001). There were no Grade 3 or higher acute complications. The 4-year rate of late Grade 3 or higher toxicity was 2.7%.
Conclusions
Clinical outcomes of pts with primary and recurrent vaginal cancer treated definitively in a systematic manner with combination EBRT with image-guided HDR BT utilizing a MCVC applicator demonstrate high rates of local control and low rates of severe morbidity. The MCVC technique allows interstitial implantation to be avoided in select pts with ≤7 mm residual disease thickness following EBRT while maintaining excellent clinical outcomes with extended 4-year follow-up in this rare malignancy.
Related Questions
For vaginal cuff recurrence of an endometrial cancer, when do you utilize a multichannel cylinder versus single channel cylinder if a patient has <5 mm residual disease after EBRT?
If disease is confined to one wall, favor MC applicator as I treat vaginal wall thickness for side involved while surface on other side. MC allows that flexibility.Here is the link to our publicationGebhardt et al., PMID 29929925
What is your dose-fractionation for cylinder-based vaginal cuff HDR brachytherapy for an isolated vaginal cuff recurrence after whole pelvis EBRT with residual thickness of disease <5 mm?
I usually prescribe 5Gy x5. I don't prescribe to a fixed thickness but treat based on residual thickness seen on MRI using multichannel applicator.I lesion at apex then treat upper 2-3 cm of vagina Here is out paper describing technique and outcome in detailhttps://www.ncbi.nlm.nih.gov/pubmed/299299...
Do you have any normal tissue constraints for endometrial cancer patients receiving EBRT and vaginal cuff brachytherapy?
We use following constraints for EBRT35 Gy to less than 35% of bowel bagRectum 40 Gy less tha 40-60% Bladder 40 Gy less than 40-60%Bone marrow ( pelvic bone) V20 less than 75% Femoral heads V35 less than 5%for brachy as adjuvant we give 5 Gy x2 to thickness of vaginaSince total dose loss limit and p...