Prognostic Value of Anteroposterior Extension in Oral Tongue and Floor Squamous Cell Carcinoma

Importance: The tongue and oral floor represent the most involved subsite by oral cancer, and there are no reported systems to classify anteroposterior tumor extension with prognostic effect. In other cancers, the anterior vs posterior tumor extension is a relevant prognostic factor. Objective: To establish whether anterior vs posterior tumor extension may represent a prognostic factor in oral tongue and floor squamous cell carcinoma (OTFSCC). Design, setting, and participants: This was a retrospective cohort study of patients who underwent surgery for OTFSCC from January 1, 2010, to December 31, 2021, at 2 tertiary-level academic institutions in Italy (University of Padua and University of Brescia). Patients eligible for the study had histologically proven primary OTFSCC; underwent surgery-based, curative treatment; and had available preoperative contrast-enhanced imaging. Exposures: Four anatomical lines were designed to assess tumor extension: (1) chin-palate line (CPL), (2) chin-basion line, (3) Stensen duct line, and (4) lingual septum line. Preoperative imaging was re-evaluated, and tumor extension was classified as either anterior or posterior according to the lines. Main outcomes and measures: Overall survival and time to recurrence (TTR) were evaluated according to tumor extension. These outcomes were reported as 5-year survival rates with 95% CIs. Results: Of the 133 patients included, 79 (59.4%) were male, and the mean (SD) age was 62.7 (15.4) years. The 5-year TTR difference was higher for posterior vs anterior OTFSCC classified according to CPL (21.0%; 95% CI, 8.3%-33.7%), Stensen duct line (15.5%; 95% CI, 1.0%-30.0%), and lingual septum line (17.2%; 95% CI, 2.2%-32.3%). Overall survival analysis showed similar results. At the multivariable analysis on TTR, N status (adjusted hazard ratio [HR], 3.0; 95% CI, 1.2-7.1) and anteroposterior classification according to CPL (adjusted HR, 7.1; 95% CI, 0.9-54.6) were the variables associated with the highest adjusted HRs. Conclusions and relevance: In this cohort study, OTFSCC with a posterior extension to the CPL was associated with a higher risk of recurrence and death. This analysis suggests that the poor prognosis conveyed by the posterior tumor extension is independent of other relevant prognosticators except for the burden of nodal disease. This estimate is not precise and does not allow for definitive clinically important conclusions; therefore, further prospective studies are necessary to confirm these data.