Orbital Apex Involvement in Sinonasal Intestinal-Type Adenocarcinoma: Impact on Distant Metastasis and Mortality

Abstract Sinonasal intestinal-type adenocarcinoma (ITAC) is often diagnosed at advanced stages. Prognosis is strongly influenced by tumor extension into critical anatomical regions contiguous with the orbit and skull base, where achieving negative margins is challenging. To identify predictors of distant metastasis and disease-specific mortality in patients with ITAC, focusing on involvement of critical anatomical structures. Retrospective analysis of ITAC cases diagnosed between 2010 and 2024 at a tertiary center. Data on clinical presentation, imaging, histopathology, treatment modalities, and outcomes were collected. Uni- and multivariate analyses were performed to identify predictors of distant metastasis and disease-specific mortality. Thirty-four ITAC cases were included. Distant metastasis occurred in 21.2% of cases; orbital apex (p = 0.007) and pterygopalatine fossa (p = 0.034) involvement were significant in univariate analysis, with only orbital apex remaining significant in multivariate analysis (p = 0.024). Regarding ITAC-specific mortality, orbital apex involvement (p = 0.002), relapse (p = 0.043), and adjuvant radiotherapy (p = 0.045) were associated factors, with radiotherapy showing a protective effect. Multivariate analysis confirmed orbital apex as a predictor of mortality (p = 0.002), while adjuvant radiotherapy had a borderline association (p = 0.050). Orbital apex involvement independently signals high risk of distant metastasis and disease-specific death in ITAC; such patients merit individualized, intensified multimodal management. Adjuvant radiotherapy may confer a protective benefit, particularly in advanced-stage disease.