PURPOSE: The objective was to assess the local oncological outcomes of endoscopic versus external surgical treatment of sinonasal intestinal-type adenocarcinomas (ITAC) and the factors of recurrence. METHODS: a retrospective non-randomized case-control multicenter study was carried out, including 452 untreated sinonasal ITACs recruited from 10 tertiary referral centers. The tumors were re-classified according to the UICC 2017 (pT). Survival curves were obtained using the Kaplan-Meier method. Univariate analysis was done with the log-rank test. Multivariate analysis was performed with a Cox model adjusted for age, T stage, and radiotherapy. A binary logistic regression compared surgical complications and performed two supplementary analyses on positive margins. RESULTS: We compared 195 and 257 patients operated by the external and endoscopic approach, respectively. The mean follow-up was 59.2 ± 48.7 months. Post-operative margins were invaded in 30.6 versus 18.9% of patients, respectively (p = 0.007). The overall recurrence rate was 33.8 versus 24.6%, respectively (p = 0.034). There was a significant difference in favor of the endoscopic approach regarding local recurrence-free survival thanks to better surgical margins in univariate and multivariate analysis (Odd Ratio = 2.01 (1.2-3.36) p = 0.0087). The complication rate (Odds Ratio = 3.4 (1.79-6.32) p < 0.001) was significantly lower in the endoscopic group. The histological positivity of signet-ring cells shows a statistically significant difference in recurrence-free survival (p = 0.0028). CONCLUSION: the oncological control of ITAC is better through the endoscopic approach, with negative margins and the absence of signet-ring-cells, two independent factors of recurrence.Read less <