Palatoglossus Muscle and T4 Category in the Eighth Edition of TNM Staging System for OPSCC

Objective: The present study challenges the appropriateness of considering invasion of the palatoglossus muscle (PGM) as a criterion for staging oropharyngeal squamous cell carcinoma (OPSCC) as T4. Study design: Retrospective observational study. Setting: Tertiary University Hospital. Methods: This retrospective study included nonmetastatic OPSCC patients treated with curative intent at the University of Trieste, Italy from 2015 to 2021. Patients were categorized into 4 groups: (1) tumors classified as T1-T2 by both International Cancer Control (UICC) and American Joint Committee on Cancer (AJCC)-TNM; (2) T1-T2 tumors upgraded to T4 solely by UICC due to oropharyngeal PGM infiltration; (3) T1-T2 tumors upgraded to T4 by both UICC and AJCC due to oral PGM infiltration; (4) tumors classified as T3-T4 by both UICC and AJCC. Kaplan-Meier analysis estimated overall survival (OS) and disease-free survival (DFS). Multivariable Cox models, adjusted for clinical factors, assessed the impact of palatoglossus invasion on outcomes over 5 years. Results: A total of 121 consecutive patients with primary OPSCC were included (median [interquartile range] age 65 years [58-74]; 63% male). While patients with upgraded T4 category due to infiltration of the oral portion of the PGM exhibited a prognosis superimposable on that of other patients with advanced stage disease, those with upgraded T4 category due to infiltration of the oropharyngeal portion of the PGM displayed OS and DFS comparable to T1-T2 patients. Conclusion: Our findings highlight that invasion of the oropharyngeal portion of the PGM may not be a suitable criterion for staging OPSCC as T4. Further research involving larger and independent patient cohorts is strongly encouraged to corroborate these observations.