The role of neck dissection and postoperative adjuvant radiotherapy in cN0 patients with PNI-positive squamous cell carcinoma of the oral cavity.

INTRODUCTION: Loco-regional recurrence is one of the main causes of treatment failure in patients with oral squamous cell carcinoma (OSCC). Perineural invasion (PNI) is widely accepted as an oncologic feature strongly associated with aggressive behavior, disease recurrence and poorer prognosis. This study investigated the role of PNI in OSCC patients, regarding the controversial issues of its impact on loco-regional recurrence, neck management and postoperative adjuvant treatment decisions.

MATERIALS AND METHODS: A total of 367 patients with OSCC were analyzed at a tertiary care cancer center with the purpose of investigating the prognostic significance of PNI regarding neck involvement, local recurrence, regional recurrence and disease-specific survival. Two subgroups of 39 patients each, one with PNI-positive and one with PNI-negative tumors, but otherwise similar histopathological features, were retrospectively analyzed. All patients had negative resection margins, no lympho-vascular invasion and pN0-1 disease without ECS. The mean follow up period was 42.7 months.

RESULTS: Univariate and multivariate analyses showed that the perineural invasion was an independent prognostic factor for lymph node metastasis and regional recurrence, but not for local recurrence. Elective neck dissection was strongly associated with a lower risk of regional recurrence, as well as with a better disease-specific survival, in PNI-positive cN0 patients. Postoperative radiation therapy appears not to reduce the incidence of recurrence.

CONCLUSION: Perineural invasion should be considered as an independent predictor for cervical lymph node involvement. Elective neck dissection could therefore be an indicator in improving neck control and subsequently disease-specific survival in cN0 patients with PNI-positive SCC.