A novel endoscopic sleeve en bloc resection for sinonasal mucosal melanoma: A propensity score–matched comparison with conventional endoscopic surgery.

Abstract

e18150 Background: Sinonasal mucosal melanoma (SNMM) is a rare and aggressive malignancy for which complete surgical excision with negative margins remains the cornerstone of treatment, yet achieving en bloc resection through an endoscopic approach remains challenging because of complex anatomy and the skip-lesion growth pattern. Most endoscopic resections are performed piecemeal, potentially compromising margin control. We developed an endoscopic sleeve en bloc resection(ESER) technique to facilitate circumferential mucosal excision and improve oncologic completeness. This study evaluated the feasibility, safety, and preliminary oncologic outcomes of this approach compared with conventional endoscopic resection. Methods: Patients with T3N0M0 SNMM treated derived from a prospective single-arm study registered at the Chinese Clinical Trial Registry (ChiCTR2100046498) were included. Seven patients underwent ESER, and thirteen patients treated with conventional endoscopic resection were selected as matched controls using propensity score matching (PSM). Treatment modalities, surgical margin status, adverse events, recurrence, and survival outcomes were analyzed. Overall survival (OS) was the primary endpoint. Survival analyses were performed using Kaplan–Meier methods, log-rank tests, and inverse-probability weighting (IPW) to estimate the average treatment effect. Results: A total of 20 patients were analyzed (median age, 65 years; range, 39–79). Negative surgical margins were achieved in 85.7% of patients in the ESER group (n=7) and 76.9% in the conventional group (n=13). Most patients in both groups received multimodal therapy, including radiotherapy, chemotherapy, and immunotherapy. At a median follow-up of 5.5 months (range, 2–24) in the ESER group, no local recurrence, distant metastasis, or deaths were observed (OS 100%). In the conventional group, with a median follow-up of 29 months (range, 6–46), the 2-year OS was 59.8%, with three locoregional recurrences and three distant metastases. IPW analysis suggested a lower estimated risk of death with sleeve resection (ATE −0.275; p = 0.107), although the difference was not statistically significant. Treatment-related adverse events were predominantly Grade 1–2. No Grade 4 or 5 toxicities were observed. Grade 3 events were uncommon and included olfactory loss, chemotherapy-related leukopenia, and atrial fibrillation following combined therapy. Conclusions: ESER is a feasible and safe surgical approach for selected patients with SNMM, enabling true en bloc mucosal excision with acceptable morbidity. Preliminary results demonstrate favorable margin control and encouraging early oncologic outcomes. Longer follow-up and larger, multi-center studies are required to validate the long-term survival benefit and reproducibility of this technique. Clinical trial information: ChiCTR2100046498.