Long-term outcomes of SINTART 1 and SINTART 2: Two phase II trials of multimodal treatments in patients with locally advanced sinonasal carcinomas.

6120 Background: Sinonasal carcinomas (SNCs) are rare malignancies with poor prognosis. Multimodal treatments including induction chemotherapy (ICT), surgery and radiotherapy (RT) - modulated by histology and response to ICT - are often used, aiming to improve oncological outcome in terms of local control and survival. Two phase II clinical studies published in 2023 assessed the role of ICT in SNCs, SINTART1 and 2 for resectable and unresectable tumors, respectively [PMIDs: 37164774, 37163806]. The current work aims at reporting the long-term follow-up (FUP) data for both trials. Methods: The FUP was updated as of January 2026 for patients enrolled in both clinical studies. Median FUP was estimated with reverse Kaplan-Meier method. The following survival times were analyzed with Kaplan-Meier method in each cohort: overall survival (OS), disease-free survival (DFS), loco-regional-free survival (LRFS), distant metastasis-free survival (DMFS). Results: The updated median (m) survival times (in months) with their 95% confidence intervals (CI) and the event rates are detailed in Table 1. Pooling together the 2 studies, 30% of patients (18/60) were alive at last follow-up. Conclusions: SINTART 1 and 2 represent, to date, the largest prospective cohorts with long-term survival data in SNCs. With a median FUP exceeding 9 years, these results provide a robust benchmark for ICT-based multimodal strategies in this setting. Survival outcomes remain consistent with the initial reports, indicating that prognosis is largely determined within the first 2-3 years, when most deaths occur (approximately 70%). The near-overlap of mDFS and mLRFS identifies loco-regional failure as the predominant pattern of recurrence. Moreover, the short interval between relapse and death underscores the limited opportunity for salvage. These findings collectively emphasize the need for more effective local-intensification approaches and novel systemic agents. Additional analyses are underway to identify prognostic and predictive factors. Clinical trial information: NCT02099175 ; NCT02099188 . Resectable (SINTART1)N=35 Unresectable (SINTART2)N=25 mFUP (95% CI) 108.26 (97.37-129.84) 103.22 (91.68-NR) mOS (95% CI)Events 37.53 (21.97-98.36)66% 27.07 (11.28-65.03)76% mDFS (95% CI)Events 26.25 (15.43-80.43)71% 17.1 (7.89-37.76)80% mLRFS (95% CI)Events 26.25 (15.43-80.43)71% 18.95 (7.89-39.05)80% mDMFS (95% CI)Events 34.47 (21.84-96.32)69% 26.88 (9.31-46.78)76%