A Study of Prognostic Significance of Perineural Invasion in Oral Squamous Cell Carcinoma

Objective: To measure the frequency of perineural invasion in oral squamous cell carcinoma, to correlate its presence with various variables and to assess its impact upon prognosis.

Design: A retrospective analytical study was planned.

Place and Duration of study: Patients were identified with oral squamous cell carcinoma who had underwent surgical excision over the past 7 years in Rehman Medical institute. The duration of the study was 6 months.

Methodology: Pathology reports were collected; and based upon the presence or absence of PNI, Patients were divided in to two groups. The group with PNI were analyzed for a set of associations and then compared with other group for comparison. PNI frequency was correlated with age, gender, site, size and differentiation of tumor. Presence of PNI, number of tumor foci along the perineural region and the size of nerve involved were then correlated with presence or absence with nodal disease and frequency of recurrence in these cases. Results were compiled and statistically analyzed using chi square test.

Results: Total number of Patients included in study were 59. PNI was found present in 13 (22.03%) patients. PNI was found mainly in middle age group. Gender distribution: male-7, female-6 (p=0.454); Site distribution; Tongue carcinoma-6, other sites-7 (p=0.618); Size: T3-10, T1-3 (p=0.330); Differentiation: well differentiated-10, Moderate Differentiated-3 (p=0.197). Association of nodal status with PNI found positive in 6 patients (p=0.000). Association of recurrence with PNI was also found positive in 6 patients (p=0.001). Number of foci of perineural invasions (1 focus-7, 11 foci-1, 3 foci-3, 4 foci-1, 5 foci-1) association with recurrence (6 cases) p=0.535 and lymph node metastasis (6 cases) p=0.490. Nerve size involved by PNI (<1mm-3, >1mm-10) association with either lymph node metastasis (6) p=0.672 or recurrence in the neck (6) p=0.417.

Conclusion: The frequency of PNI was 22.03%. Statistically, no significant association was found between PNI and age, gender, site, grade of tumor and size of the tumor. Significant Association was found in this study between occurrence of PNI with Lymph Node metastasis and Neck Recurrence. No Significant Association was found between number of foci of Perineural invasions or the size of the nerve involved with either lymph node metastasis or recurrence.

Keywords: Perineural invasion; Oral squamous cell carcinoma; Prognostic factors