Madoka Sakuramachi

Gel spacer-assisted salvage brachytherapy for pelvic recurrence after definitive chemoradiotherapy in cervical cancer: A single-institution retrospective study

To evaluate the safety and efficacy of gel spacer-assisted high-dose-rate (HDR) salvage brachytherapy for pelvic recurrence after definitive chemoradiotherapy (CRT) for cervical cancer. We retrospectively analyzed 15 consecutive patients who underwent salvage HDR interstitial brachytherapy for pelvic recurrence following definitive CRT for cervical cancer between 2016 and 2024. Gel spacers were injected between the recurrent tumors and adjacent organs at risk (OARs), mainly the rectum and bladder, under transrectal ultrasound guidance at each brachytherapy session. The spacer's effectiveness was evaluated by comparing the hypothetical dose delivered to the gel spacer volume (assuming no spacer was used) with the actual dose to the OARs. The median biological equivalent dose in 2-Gy fractions (EQD2, α/β = 10) delivered during reirradiation was 64.0 Gy (range: 44.5-72.0 Gy). After a median follow-up of 22 months (range: 0-93 months), the complete response rate was 66.7% (10/15). Gel spacer injection significantly reduced the rectal D2cc by a median of 29% (interquartile range [IQR]: 14%-55%) and the bladder D2cc by 16% (IQR: 10%-34%) compared with the hypothetical dose estimates assuming no spacer use (Wilcoxon signed-rank test, p < 0.001). Grade ≥3 late toxicities occurred in only one patient (10.0%) among complete responders, and no spacer-related adverse events were observed. Gel spacer-assisted salvage brachytherapy significantly reduced radiation exposure to critical OARs, particularly the rectum, while achieving effective tumor control in patients with pelvic recurrence of cervical cancer after definitive CRT. These promising results support this approach as a feasible and safe strategy, warranting further validation in larger prospective studies.

Role of the gel spacer in safely delivering whole pelvic radiation therapy without central shielding in computed tomography-based image-guided adaptive brachytherapy for uterine cervical cancer patients

To protect the rectum and bladder from high dose exposure, the Japanese guidelines for managing uterine cervical carcinoma recommend pelvic irradiation with central shielding (CS). Conversely, the European Society for Radiotherapy and Oncology (ESTRO) and the American Brachytherapy Society (ABS) guidelines recommend delivering ≥85 Gy to high-risk clinical target volume D Twenty patients who received definitive radiation therapy without CS and were treated by brachytherapy with a gel spacer between 2017 and 2022 were retrospectively reviewed. The cumulative doses of EBRT and brachytherapy treatment outcomes and incidence of adverse events were also examined. The median cumulative CTV The use of gel spacer can enable ESTRO/ABS-recommended dose constraints even without using CS in EBRT, with favorable outcomes and low adverse event rates.

Salvage image-guided freehand interstitial brachytherapy for pelvic sidewall recurrence after hysterectomy for uterine malignancies

Pelvic sidewall recurrence after hysterectomy for uterine malignances has a poor prognosis, and the salvage therapy for this type of recurrence is still challenging. The purpose of this study was to investigate the efficacy of freehand high-dose-rate interstitial brachytherapy (HDR-ISBT) through the perineum using transrectal ultrasonography for this disease. We retrospectively evaluated 42 patients with pelvic sidewall recurrence after hysterectomy for uterine cervical and endometrial cancers. We investigated patients' characteristics, the 2-year local control and survival rates, and late adverse events of the rectum and bladder. The 2-year overall survival, local control, and progression-free survival rates were 73.7% (95% confidence interval [CI], 60.8-89.3%), 69.4% (95% CI, 55.4-80.1%), and 37.3% (95% CI, 24.6-56.5%), respectively. In Cox multivariate analysis, tumor size at recurrence (<45 mm vs. ≥45 mm) (p = 0.04) and disease-free periods after hysterectomy (<10 months vs. ≥10 months) (p < 0.01) were significant prognostic factors for overall survival. Lymph node metastasis at recurrence (p < 0.01) was also a significant prognostic factor for progression-free survival. Three patients experienced Grade 3-4 late proctitis (7%). Transperineal freehand salvage HDR-ISBT using transrectal ultrasonography was demonstrated to be a curative treatment option for patients with pelvic sidewall recurrence following hysterectomy. Based on the findings of this study, we emphasize the importance of HDR-ISBT for pelvic sidewall recurrence.

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

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