Long-term and short-term prognostic value of the prognostic nutritional index in cancer: a narrative review

Objective: To perform a narrative review of the prognostic value of prognostic nutritional index (PNI) in cancers. Background: Prognostic estimation greatly determines the treatment approach in various cancers. The prognostic nutritional index (PNI), calculated using the serum albumin level and total lymphocyte count, is a useful indicator to assess nutritional and immunological conditions. The PNI represents a low-cost, easy-to perform, noninvasive, rapid, and standardized tool for estimating the prognosis of cancer. Many studies have aimed to clarify the prognostic value of PNI for various types of cancer. Methods: We summarize the studies, particularly the systematic reviews and meta-analyses, that have examined the prognostic value of PNI in common cancers. Conclusions: The relevant studies indicate that low PNI is an independent prognostic factor for decreasing overall survival in many types of cancers. Disease-free survival and progression-free survival were also associated with PNI in some types of cancer including lung cancer and renal cell carcinoma. Therefore, we suggest that the measurement of PNI is a useful method to identify cancer patients that have a worse prognosis and that the treatment strategy for these patients be adjusted accordingly. We hypothesize that maintaining good nutritional status during treatment may improve outcomes of various cancers.