Background: The past two decades have seen a paradigm shift in the surgical treatment of sinonasal malignancies, moving from traditional open approaches to minimally invasive endoscopic techniques. Technological advancements have enabled the use of the endoscopic endonasal transcribriform approach (EETA) for tumors involving the anterior skull base (ASB). This study evaluates the oncologic outcomes of EETA for locally advanced sinonasal malignancies with ASB involvement.

Methods: We conducted a retrospective cohort study at a tertiary cancer center, including patients treated with EETA for sinonasal malignancies from January 2012 to January 2024. Data on demographic characteristics, clinical presentations, treatment protocols, and survival outcomes were analyzed. Survival probabilities were assessed using Kaplan-Meier curves, and subgroups comparisons were made using the log rank test.

Results: Forty-nine patients were included, predominantly with primary tumors (91.8%) and advanced stages (cT3-T4: 89.8%). EETA achieved R0 resection in 82.1% of cases. All eligible patients (88.9%) underwent postoperative radiotherapy, with 97.5% beginning treatment 6-8 weeks after surgery. The mean follow-up duration was 43.2 months. The 5-year overall survival (OS) was 66.5%, disease-free survival (DFS) was 58.7%, and local relapse-free survival (LRFS) was 75%. Patients with olfactory neuroblastoma had significantly higher OS and DFS compared to intestinal-type adenocarcinoma. Margin status significantly impacted survival, with better outcomes observed in patients with clear margins.

Conclusions: EETA offers a viable and effective alternative for treating locally advanced sinonasal malignancies with ASB involvement, achieving acceptable oncologic outcomes with reduced morbidity.