Evaluation of the dosimetric impact and safety of MucoUp as a spacer in gynecologic brachytherapy.

Abstract

Background: Gynecologic brachytherapy (BT) is an essential component of definitive radiation therapy, but excessive radiation exposure to organs at risk (OARs) remains a major concern. MucoUp, a hyaluronic acid-based spacer, has been introduced to physically separate the high-risk clinical target volume (HR-CTV) from adjacent OARs. However, its clinical feasibility and dosimetric impact remain underexplored.

Objective: This study aimed to evaluate the dosimetric impact and clinical feasibility of MucoUp in high-dose-rate (HDR) gynecologic BT.

Methods: A retrospective analysis was conducted on 5 patients with gynecologic malignancies who underwent HDR BT with and without MucoUp injection. Dosimetric parameters, including HR-CTV D90 and OAR D2cc (bladder, rectum), were compared between sessions with and without MucoUp. Spacer volume retention was assessed using pre- and post-treatment CT scans.

Results: MucoUp injection resulted in a significant reduction in rectal D2cc (7.19 Gy vs. 6.73 Gy, p = 0.043), while maintaining HR-CTV dose coverage (D90: 8.82 Gy vs. 9.15 Gy, p = 0.043). A nonsignificant reduction in bladder D2cc was observed (7.51 Gy vs. 7.16 Gy, p = 0.34). Spacer volume retention remained stable throughout treatment. No procedural complications or acute toxicity were observed.

Conclusion: This study suggests that MucoUp is a promising spacer for gynecologic BT, effectively reducing rectal dose while preserving HR-CTV coverage. Given its high stability and safety, MucoUp may serve as an alternative to existing spacer materials. Further large-scale and long-term studies are warranted to evaluate its impact on late toxicities.