Impact of Local Extent of Tumor on the Survival Outcomes for Surgically Treated Tongue Cancers.

Background: The current classification of tongue cancers does not discriminate stages based on factors of local spread.

Aim: Integrating factors of local spread that impact disease-specific survival (DSS) in a modified classification to improve prognostication compared with the current staging.

Method: This was a retrospective analysis of 399 previously untreated oral tongue squamous carcinomas operated between 2016 and 2018. Factors related to the local extent of a primary tumor that impacted the DSS were studied. Multivariable analyses adjusted for pT, pN stage, and adjuvant therapy. Candidate staging systems were developed based on factors that significantly impacted DSS, and validated.

Result: Base tongue involvement (p = 0.021), DOI > 20 mm (p value = 0.040), and tumor crossing the midline (p value = 0.047) significantly impacted the DSS. The preferred model included base tongue involvement in T3 stage, and DOI > 20 mm and tumor crossing the midline into T4 stage (Model 2), which was superior to the current classification system in AIC (830.55 vs. 845.43), C-index (0.65 vs. 0.61), and visual inspection of Kaplan-Meier curves.

Conclusion: Identifying and possibly including these clinical factors in addition to the current T-stage criteria could result in better prognostication of tongue cancers.

Significance: Integration of proposed classification could improve the discrimination between stages.