Risk Stratification by Extent of Extranodal Extension and Peri‐Neural Invasion in Post‐Operative Oral Cavity Squamous Cell Carcinoma Undergoing Adjuvant Radio Therapy (
EXTENT
Study)
Sambit Swarup Nanda, Ashutosh Mukherji, Shubham Dokania, Ajay Choubey, Pritam Mondal, Ankita Pal, Akhil Kapoor, Aseem Mishra, Sunayana R. Sarkar, Ipsita Dhal, Prasenjit Nath, Minesh Patel, Shreya Shukla ABSTRACT
Background
The AJCC 8th edition recommends subclassifying extranodal extension (ENE) and perineural invasion (PNI) in oral cavity squamous cell carcinoma (OCSCC), though their prognostic relevance remains uncertain.
Methods
Post‐operative OCSCC patients (2019–2024) receiving adjuvant radiotherapy or chemoradiotherapy with documented ENE and/or PNI were retrospectively analyzed. ENE (microscopic [miENE] vs. macroscopic [maENE]) and PNI (intratumoral [IPNI] vs. extratumoral [EPNI]) were correlated with disease‐free survival (DFS), overall survival (OS), and failure patterns using multivariate Cox models.
Results
Among 410 patients (median follow‐up: 33 months), 3‐year DFS and OS were 45.6% and 53.2%. ENE subtyping did not impact DFS or OS. EPNI independently predicted inferior DFS (43.3% vs. 49.5%, p = 0.019) and OS (50.2% vs. 57.9%, p = 0.02). Combined EPNI, ENE, and lymph‐node ratio > 0.05 identified a very high‐risk subgroup.
Conclusion
ENE subclassification lacked prognostic significance. EPNI predicted worse outcomes and, with ENE or high lymph node ratio, defines an aggressive phenotype warranting treatment intensification.