Objective To investigate the value of peripheral blood neutrophil to lymphocyte ratio before and after radical operation (ΔNLR), preoperative prognostic nutrition index (PNI) and serum carcinoembryonic antigen (CEA) levels in predicting the poor prognosis of patients with colorectal cancer (CRC) after radical resection.

Methods The clinical data of 182 patients treated with radical operation of CRC were retrospectively analyzed, and the patients were divided into the good prognosis group and poor prognosis group according to the survival conditions at 5 years after operation. The ΔNLR in peripheral blood, preoperative PNI and serum CEA levels were compared between two groups, and the Cox regression was used to analyze the independent influencing factors of poor prognosis of CRC patients after radical surgery, and the receiver operating characteristic (ROC) curve was used to analyze the predictive efficacy of ΔNLR in peripheral blood, preoperative PNI and serum CEA levels on poor prognosis of patients with CRC after radical resection. Kaplan-Meier survival curves were drawn to compare the survival rates of patients with CRC after radical surgery with different ΔNLR, PNI and CEA levels.

Results The 5-year mortality rate of CRC patients after radical operation was 37.36% (68/182). The ΔNLR in peripheral blood and preoperative serum CEA levels in poor prognosis group were higher than those in good prognosis group (P ＜ 0.01), but the preoperative PNI was lower than that in good prognosis group (P ＜ 0.01). The proportions of patients with TNM stage of III, vascular invasion and nerve invasion in the poor prognosis group were higher than those in good prognosis group (P ＜ 0.05 to P ＜ 0.01), but there was no statistical significance in the age, gender, family history of CRC, tumor location, tumor size and operation time between two groups (P ＞ 0.05). The results of Cox regression analysis showed that the TNM stage, vascular infiltration, nerve invasion, ΔNLR in peripheral blood, preoperative PNI and serum CEA levels were the independent influencing factors of poor prognosis of CRC patients after radical operation (P ＜ 0.05 to P ＜ 0.01). The results of ROC curve showed that the sensitivity and area under the curve (AUC) of the joint ΔNLR in peripheral blood, preoperative PNI and serum CEA level in predicting the poor prognosis of CRC patients after radical operation were higher than that of single prediction (P ＜ 0.05). The results of Kaplan-Meier survival curve analysis show that the 5-year survival rates of patients with CRC after radical surgery with ΔNLR ＞ 1.87, PNI ≤ 48.87 and CEA ＞ 8.95 ng/mL were significantly lower than those patients with ΔNLR ≤ 1.87, PNI ＞ 48.87, CEA ≤ 8.95 ng/mL (P ＜ 0.01).

Conclusions The ΔNLR in peripheral blood, preoperative PNI and serum CEA levels are closely related to the prognosis of CRC patients after radical operation, and the predictive efficacy of the combination of the three is better.