ESTRO 2025 - Abstract Book

S293

Brachytherapy – Head & neck, skin, eye

ESTRO 2025

A retrospective review of the medical records of patients diagnosed with SCCNV who received HDR-IRT treatment from 2008 to 2022. Recurrences and SCC originating from the skin were excluded. Interstitial HDR-IRT catheters were implanted immediately in the operating room. The target volume encompassed the estimated tumor volume and a safety margin of 10–15 mm. The prescribed radiation dose was delivered twice daily, with a minimum interval of six hours between fractions. Treatment-related toxicities were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Results:

We identified 51 patients, with a median age of 71 years (IQR: 62–82). T-stage distribution included T1 in 30 patients (59%), T2 in 16 (31%), T3 in 3 (6%), and T4 in 2 (4%). All patients presented with negative neck lymph nodes. The median total dose of HDR-IRT was 40 Gy (IQR: 36–45), with a median fraction dose of 4 Gy (IQR: 4–4) and a median number of fractions at 10 (IQR: 9–12). Gross total resection (GTR) was achieved in 7 patients (13.7%), while subtotal resection (STR) was performed in 44 patients (86.3%). The median follow-up duration was 35 months (IQR: 20–46). The 3-year organ extirpation-free survival rate was 90% (95% CI: 79–97), with local failure-free survival at 84% (95% CI: 71–93), regional failure-free survival at 94% (95% CI: 84–99), and overall survival at 82% (95% CI: 69–92). No distant metastases were recorded. Multivariable analysis aimed at identifying factors associated with treatment failure yielded no significant results. Factors analyzed included T-stage, tumor grade, varying dose levels, and type of surgery performed (GTR versus STR). In total, 49 instances of acute toxicities were documented in 37 patients, including only two grade-3 events and no grade-4 events. The most commonly reported acute toxicity was radiodermatitis (40%). Chronic toxicities amounted to 38 events in 22 patients, with just one grade-3 event and no grade-4 events recorded. Conclusion: OSIRIS approach combining HDR-IRT with organ-preserving surgery appears to be an effective treatment for SCCNV, demonstrating high rate of organ preservation along with favorable long-term disease control rates and treatment related toxicity rates.

Keywords: Brachytherapy, nasal vestibule cancer