The prognostic importance of midline involvement in oral tongue cancer

To examine the importance of midline involvement and other clinicopathologic factors in predicting the rate of contralateral lymph node metastasis and survival in oral tongue squamous cell carcinoma.

We used Surveillance, Epidemiology, and End Results data to identify a cohort of 5430 patients with laterally rising tumors. Clinicopathologic factors examined as potentially predictive of contralateral lymph node metastasis included extension to midline, T classification, anatomic site, grade, histologic subtype, race, age, and sex. Survival analysis included the above factors plus lymph node status.

T1 tumors and lateral T2 and T3 tumors had rates of contralateral lymph node metastasis ranging from 0.7% to 0.9% on presentation. T4 lesions and midline crossing T2 and T3 lesions had corresponding rates of 8.3% to 13.0%. Primary extension across the midline was associated with a mean survival about half that of strictly lateral tumors and its significance was maintained in multivariate analysis.

Patients with T1 disease or T2-3 disease that does not cross midline are in a different prognostic class from patients with T2-3 disease that crosses midline or T4 tumors. These results give the strongest evidence to date that involvement of the midline is a powerful predictor for decreased survival in oral tongue squamous cell carcinoma.