Post-Treatment Surveillance in Sinonasal Malignancies: A Systematic Review of Recurrence Patterns and Diagnostic Modality Performance

Background: Sinonasal malignancies constitute a rare subset of head and neck cancers (HNC) and pose substantial clinical challenges due to their aggressive biology, complex anatomy, and high rates of asymptomatic locoregional recurrence. Current surveillance protocols are largely extrapolated from general HNC guidelines, which often fail to account for the unique recurrence patterns and histologic variability of sinonasal tumors. Objective: To systematically evaluate post-treatment surveillance of sinonasal malignancies, with emphasis on recurrence patterns and diagnostic modality performance. Methods: A systematic review was conducted in accordance with PRISMA guidelines. EMBASE and MEDLINE databases were queried to identify studies reporting on post-treatment surveillance in sinonasal malignancies. Studies were excluded if published before 2000, non-English, non-sinonasal cancer population, or involving pediatric populations. Extracted data included recurrence patterns and diagnostic performance of surveillance modalities. Risk of bias was assessed using the Newcastle-Ottawa Scale. Certainty of evidence was assessed using the GRADE approach. Results: Of 2,819 records, 13 studies met inclusion criteria. Recurrence rates in sinonasal cancers varied by tumor type. The highest rates were seen in mucosal melanoma (MM) and sarcoma, followed by sinonasal undifferentiated carcinoma (SNUC). Moderate recurrence was observed in olfactory neuroblastoma (ONB) and adenoid cystic carcinoma (ADCC), with the lowest rates in squamous cell carcinoma (SCC). Most recurrences occurred locally, followed by regional and distant failures. Time to recurrence differed, with aggressive tumors like MM and neuroendocrine carcinoma (NEC) recurring early, while sarcoma, ONB, and ADCC recurred later. Recurrence timing also depended on site, with intracranial and distant metastases appearing after longer intervals. Diagnostic methods varied in performance: PET/CT demonstrated the highest sensitivity and negative predictive value; MRI provided the greatest specificity but only moderate sensitivity; CT achieved perfect specificity with moderate sensitivity; and endoscopy showed low sensitivity but high specificity. Conclusion: Patterns of recurrence in sinonasal malignancies differ markedly by histology, timing, and anatomical site. Existing HNC surveillance guidelines are nonspecific and insufficiently address these rare tumors, limiting their applicability in clinical practice. Given the variable diagnostic performance across imaging modalities, surveillance strategies should be histology-adapted and multimodal. High-quality prospective studies are urgently needed to establish evidence-based surveillance protocols. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany