The prognostic value of the prognostic nutritional index in patients with metastatic colorectal cancer

Objective: The prognostic nutritional index (PNI) has been shown to be prognostic value for many types of cancer of the gastrointestinal system. However, there are limited data on its value for metastatic colorectal cancer (mCRC). This study aimed to evaluate the prognostic value of PNI in newly diagnosed mCRC patients.

Methods: The data of 468 patients who had been admitted to our center upon being diagnosed with mCRC between January 2010 and December 2017 were reviewed retrospectively, whereby satisfying the inclusion criteria were included in the study. Receiver operating characteristic (ROC) analysis was used for PNI's optimum cut-off value for overall survival (OS). The Cox regression model was used in the single-variable analysis in order to test whether or not variables with prognostic properties were independent prognostic factors.

Findings: A total of 308 patients were included in the study. Sixty-two percent (n = 192) of the patients were males, and the median age was 57.5 years (range: 25-83). Forty-five percent (n = 137) of the patients had KRAS mutation. Tumors localized in the colon accounted for 63% (n = 193) of the patients. The liver was the most common region of metastasis at 69%. According to the ROC curve, the optimal cut-off value for PNI was 46 (sensitivity 74%, specificity 47%, AUC 0.615, 95% confidence interval [CI]: 0.54-0.68, P = .002). One hundred and eighty-two patients (59%) fell into the PNI-High (> 46) group, while 126 patients (41%) fell into the PNI-Low (≤ 46) group. The rectum localization was higher, whereas the neutrophil-lymphocyte ratio and platelet-lymphocyte ratio were lower in the PNI-High group. There was no difference in terms of other patient characteristics. The median OS was significantly longer in the PNI-High group compared to the PNI-Low group (28.4 vs 19.1 months, P < .001). The Cox regression analysis showed that a high PNI was an independent positive prognostic factor (hazard ratio: 0.61, 95% CI: 0.42-0.87, P = .007).

Discussion: We found PNI to be an independent prognostic factor in mCRC. We think that PNI, which can be calculated by a simple formula, may provide clinicians important clues in order to make desicion for individual treatment.