Treatment for T1-2 Oral Squamous Cell Carcinoma with or Without Perineural Invasion: Neck Dissection and Postoperative Adjuvant Therapy

Although perineural invasion (PNI) has been a poor prognostic factor for head and neck cancers, few studies have focused on oral squamous cell carcinoma (OSCC). The independent significance of PNI in early T1-2 OSCC and the benefit of treatment modification based on PNI status have not been assessed. This study investigated the role of PNI in T1-2 OSCC patients, with focus on the controversial issues of neck management and postoperative adjuvant therapy. PNI status was re-reviewed under hematoxylin and eosin staining in tumors of 307 consecutive T1-2 OSCC patients. Oncologic and survival outcomes were analyzed by univariate and multivariate analyses. PNI was identified in 84 (27.4%) patients, correlating with several established poor prognostic factors. In multivariate analysis, PNI remained an independent predictor for neck metastasis, neck recurrence, and a worse 5-year disease-specific survival. Elective neck dissection contributed to a significantly better 5-year disease-specific survival only in cN0 patients with PNI-positive tumors ( = 0.0071) but in those with PNI-negative tumors ( = 0.3566). In low-risk patients who were treated by surgery alone, including neck dissection, the 5-year disease-specific survival rates were almost the same in those with PNI-positive tumors and those with PNI-negative tumors (92.0 vs. 92.9%; = 0.9104). Elective neck dissection is indicated for cN0 patients with PNI-positive tumors for the efficacy of improving disease-specific survival as well as neck control. However, low-risk PNI-positive patients who undergo neck dissection do not need postoperative adjuvant therapy, because the residual risk from PNI is minimal.