The prognostic significance of the prognostic nutritional index in cancer: a systematic review and meta-analysis

The prognostic nutritional index (PNI) is a simple and effective parameter, initially created to evaluate preoperative nutritional conditions and surgical risk. It has been recently been found to be associated with short- and long-term outcomes of various malignancies. We performed a meta-analysis to determine the predictive significance of PNI in cancer, as a mean to assist in determining the optimal surgery timing and in improving the survival of cancer patients. Data were retrieved from PubMed and ISI Web of Science to identify eligible studies. Odds ratios (ORs) and hazard ratios (HRs) were extracted and pooled to explore the relationships of PNI with patient survival and clinicopathological features. Fourteen studies with a total of 3,414 participants met the inclusion criteria. Low PNI was associated with poor overall survival (pooled OR 1.80, 95 % confidence interval [CI] 1.59-2.04) and the presence of post-operative complications (pooled OR 2.45, 95 % CI 1.31-4.58) in cancer patients, but not with cancer-specific survival (CSS) (pooled HR 1.81, 95 % CI 0.94-3.49). PNI was also found to be associated with invasion depth (pooled OR 5.07, 95 % CI 2.34-10.96) and lymph node metastasis (pooled OR 3.70, 95 % CI 2.32-5.92) in gastric cancer, whereas TNM stage was the only clinicopathological feature associated with PNI in colorectal carcinoma (pooled OR 1.81, 95 % CI 1.24-2.64). PNI might be an effective predictive indicator for the prognosis of cancer, especially digestive system carcinomas. Further studies are required to verify the significance of PNI in clinical practice.