The Prognostic Importance of Midline Involvement in Oral Tongue Cancer

Abstract

Objectives To examine the importance of midline involvement and other clinicopathological factors in predicting the rate of contralateral lymph node metastasis and survival in oral tongue squamous cell carcinoma. Methods We used SEER data to identify a cohort of 5430 patients with laterally rising tumors. Clinicopathological factors examined as potentially predictive of contralateral lymph node metastasis included extension to midline, T classification, anatomical site, grade, histological sub-type, race, age, and gender. Survival analysis included the above factors plus lymph node status. Results T1 tumors and lateral T2 and T3 tumors had rates of contralateral lymph node metastasis ranging from 0.7-0.9% 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. Conclusions Patients with T1 disease or T2-3 disease that doesn’t 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.

Midline involvement and perineural invasion predict contralateral neck metastasis that affects overall and disease-free survival in locally advanced oral tongue squamous cell carcinoma

“…In this study of TSCC, the incidence of CLNM was as high as 34.4% (11 of 32 patients), presumably because the subjects were limited to locally advanced stage cT3–4a tumors. In line with this, among previous studies that confined the subjects to laterally arising TSCC, a study that screened all stages using a population-based cancer registry, in which cT1–2 constituted 70% of the cohort, showed a very low CLNM incidence of 2.5% ( 10 ). In contrast, a study that exclusively analyzed patients with primary tumors that crossed the midline, in which cT3–4 constituted 82% of the cohort, reported a relatively high CLNM incidence of 29.2% ( 24 ).…”

“…Previous studies have reported an incidence of CLNM in OSCC ranging from 0.9% to 36% ( 9 , 10 , 22 – 24 , 27 – 31 ). Such wide variance seems to be attributable primarily to differences in patient eligibility criteria in terms of anatomic subsites, location, and stage of the tumor, as well as disparity in standard treatment strategies and histopathological processing at each institution.…”

“…Previous studies have reported several clinicopathological factors associated with CLNM in TSCC ( 9 , 10 , 22 – 24 ). However, no consensus has been reached on these factors, likely because the eligibility criteria for inclusion were inconsistent across the studies, complicating comparisons among studies much more than in studies regarding ipsilateral neck metastases in early T stage cases.…”

“…In addition, since this rich lymphatic network freely communicates across a fibrous septum that constitutes the midline of the tongue, TSCC that has reached the tongue midline has an increased chance of metastasis to the lymph node in the contralateral side of the neck ( 5 , 6 ). Although contralateral neck metastasis (CLNM) develops much less frequently than ipsilateral metastasis, patients with OSCC, including TSCC, who have developed CLNM have even worse survival rates ( 7 – 10 ).…”

“…Indeed, it is often difficult to judge whether to perform elective neck dissection for the contralateral cN0 neck (i.e., bilateral neck dissection for <cN2c patient), because it also involves a dilemma between improving tumor control and decreasing postoperative function, even in advanced stage patients. In addition, few reports of determinants of CLNM have been corroborated by multivariate analysis ( 10 , 22 – 24 ), as compared with those regarding the predictors of ipsilateral nodal metastasis, such as DNM.…”