Radiological Sublingual Space Invasion in Tongue Squamous Cell Carcinoma: Clinicopathological Associations and Impact on Survival.

OBJECTIVES

We investigate if sublingual space invasion (SLI) determined on magnetic resonance imaging confers differences in clinicopathological manifestations and treatment outcomes of oral tongue squamous cell carcinoma (OTSCC).

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary Academic Medical Center.

METHODS

221 OTSCC patients were included. Cox regression models and Kaplan-Meier methods were used, and nomogram construction was performed, incorporating SLI with other adverse factors, to predict the prognosis.

RESULTS

On multivariable analysis, the following were associated with cervical nodal metastasis: (1) greater MRI T classification of T3/T4 versus T1/T2: adjusted odds ratio (aOR) 2.784, 95% CI = 1.459 to 5.313, P = .001; (2) gender (female vs male): aOR 4.117, 95% CI = 1.602 to 10.576, P = .003; (3) presence of MRI-determined SLI: aOR 2.588, 95% CI = 1.393 to 4.808, P = .002. For survival outcomes, extranodal extension (adjusted hazard ratio [aHR]: 3.380, 95% CI = 2.024-5.644, P < .001), poorly-differentiated type (aHR: 1.720, 95% CI = 1.006-2.943, P = .047), lymphovascular invasion (aHR: 2.100, 95% CI = 1.220-3.614, P = .007), and SLI (aHR: 1.700, 95% CI = 1.086-2.661, P = .020) were statistically significant prognosticators of disease-free survival. In overall survival, when controlled for age, gender, overall TNM stage, Charlson morbidity index, surgical margins, depth of invasion and adjuvant therapy, SLI was a statistically significant prognosticator (aHR: 1.622, 95% CI = 1.012-2.602, P = .044). A proposed novel nomogram for overall survival combining SLI and other risk factors showed a higher concordance index compared to a nomogram with TNM staging alone (0.783 vs 0.629, P < .001).

CONCLUSION

SLI is an independent prognostic factor for treatment outcomes in OTSCC. Incorporating SLI into a novel nomogram demonstrated improved predictive accuracy for post-treatment outcomes.