Perineural invasion as a prognostic factor in patients with stage I-III rectal cancer - 5-year follow up.

BACKGROUND: Rectal cancer (RC) is one of the most common diagnosed cancers, and one of the major causes of cancer-related death nowadays. Majority of the current guidelines rely on TNM classification regarding therapy regiments, however recent studies suggest that additional histopathological findings could affect the disease course. AIM: To determine whether perineural invasion alone or in combination with lymphovascular invasion have an effect on 5-years overall survival (OS) of RC patients. METHODS: A prospective study included newly diagnosed stage I-III RC patients treated and followed at the Digestive Surgery Clinic, Clinical Center of Serbia, between the years of 2014-2016. All patients had their diagnosis histologically confirmed in accordance with both TMN and Dukes classification. In addition, the patient's demographics, surgical details, postoperative pathological details, differentiation degree and their correlation with OS was investigated. RESULTS: Of 245 included patients with stage I-III RC, lymphovascular invasion (LVI) was identified in 92 patients (38%), whereas perineural invasion (PNI) was present in 46 patients (19%). Using Kaplan-Meier analysis for overall survival rate, we have found that both LVI and PNI were associated with lower survival rates (P < 0.01). Moreover when Cox multiple regression model was used, LVI, PNI, older age, male gender were predictors of poor prognosis (HR = 5.49; 95%CI: 2.889-10.429; P < 0.05). CONCLUSION: LVI and PNI were significant factors predicting worse prognosis in early and intermediate RC patients, hence more aggressive therapy should be reserved for these patients after curative resection.