The prognostic significance of the postoperative prognostic nutritional index in patients with colorectal cancer

Background: The preoperative prognostic nutritional index (PNI) has been reported to correlate with the prognosis in patents with various carcinomas. However, the prognostic significance of the postoperative PNI is unknown. The aim of this study was to evaluate the prognostic significance of the postoperative PNI in patients with colorectal cancer (CRC). Methods: Two hundred and eighteen patients who underwent potentially curative surgery for stage II/III CRC were enrolled in this study. The PNI was calculated as 10 x serum albumin concentration (g/dl) + 0.005 x lymphocyte count (/mm(3)). The preoperative PNI was measured within two weeks before the operation and the postoperative PNI were measured at the first visit after leaving the hospital. We then examined the correlations between the preoperative/postoperative PNI and the prognosis for survival. Results: In the validation study, the median preoperative PNI was 47.90 (range: 32.45-61.36) and the median postoperative PNI was 48.69 (range: 32.62-66.96). According to the receiver operating characteristic (ROC) curve, we set 43.0 as the cut-off value in the validation study. For both the preoperative and postoperative PNI, the overall survival rates were significantly worse in the low PNI group in the validation study (preoperative PNI, rho = 0.0374; postoperative PNI, rho = 0.0005). In the multivariate analysis of the validation study, the combination of pre- and postoperative PNI was an independent predictor of poor overall survival (rho = 0.006). Conclusions: The postoperative PNI is, in addition to the preoperative PNI, a useful prognostic marker. The combination of pre- and postoperative PNI was an independent prognostic factor in patients with CRC who underwent potentially curative surgery and is important for considering the long-term outcome in patients with CRC.