Extranodal Extension and Epithelial Cell Adhesion Molecule Over-expression in Oral Squamous Cell Carcinoma

Concomitant chemoradiotherapy (CCRT) with cisplatin is commonly administered after neck dissection in patients with oral squamous cell carcinoma (OSCC) showing extranodal extension (ENE). This study investigated whether the efficacy of CCRT differed depending on the degree of ENE and whether the expression of epithelial cell adhesion molecule (EpCAM) was associated with prognosis.Patients with OSCC who underwent neck dissection and had histologically proven neck metastasis (pN+) were investigated retrospectively. ENE was divided into ENE minor (ENEmi; <2 mm) and ENE major (ENEma; ≥2 mm). The expression of EpCAM was also immunohistochemically examined using tissues obtained during neck dissection.One hundred and seventy pN+ cases [ENE(-), n=89; ENEmi, n=23; ENEma, n=58] were included. Multivariate analysis revealed that advanced T stage and ENEma were significantly correlated with poor prognosis. The 5-year disease-specific survival rates in ENE(-), ENEmi, and ENEma groups were 73.7%, 75.5%, and 28.0% respectively. An add-on effect of postoperative CCRT was not seen in the ENEmi group; however, postoperative CCRT improved the survival of patients in the ENEma group. In the ENEma group, the prognosis was significantly worse in EpCAM-positive patients than in EpCAM-negative patients.Postoperative CCRT may improve prognosis in ENEma cases. EpCAM expression may be a poor prognostic factor in ENEma cases. On the other hand, postoperative CCRT did not have a significant effect on prognosis in ENEmi cases. Among them, although there was no significant difference in the survival rate, postoperative CCRT could be omitted in ENEmi/EpCAM(-) cases.