The impact of multifocal perineural invasion in predicting survival in patients with oral squamous cell carcinoma: A multicenter investigation

Abstract Background Perineural invasion (PNI) in oral squamous cell carcinoma (OSCC) does not contribute to the current American Joint Committee on Cancer 8th edition (AJCC8) staging manual. This study seeks to validate the effect of multifocal PNI in a large cohort of patients. Methods Patients undergoing primary surgical treatment of OSCC with curative intent between 1995 and 2022 was retrieved from two Australian head and neck databases. PNI was categorized as a single focus or multiple foci. Study end points included disease‐specific survival (DSS) and overall survival (OS). Results Complete data for survival analysis was available in 993 patients. Multifocal PNI was associated with a 61% increased risk of death due to OSCC (HR 1.61, 95% CI 1.11–2.33, p = 0.014) and a 32% increased risk of death from any cause (HR 1.32, 95% CI 1.01–1.73, p = 0.045). Conclusions Multifocal PNI is a significant predictor of survival in OSCC.