Prognostic significance of preoperative prognostic nutritional index in colorectal cancer: results from a retrospective cohort study and a meta-analysis

The preoperative prognostic nutritional index (PNI) may forecast colorectal cancer (CRC) outcomes, but the evidence is not conclusive. Here, we retrospectively analyzed a cohort of patients from the Department of Surgical Oncology at the First Hospital of China Medical University (CMU-SO). We also conducted a meta-analysis of eleven cohort studies. Bayesian Information Criterion (BIC) was used to determine the optimal PNI cut-off values for classifying prognosis in the patients from the CMU-SO. The result from CMU-SO and meta-analysis both confirmed that low PNI was significantly associated with a poor prognosis and advanced TNM stages. Among the patients from the CMU-SO, the optimal cut-off values were "41-45-58" (PNI < 41, 41 ≤ PNI < 45, 45 ≤ PNI < 58, PNI ≥ 58), which divided patients into 4 stages. The BIC value for TNM staging combined with the PNI was smaller than that of TNM staging alone (-325.76 vs. -310.80). In conclusion, low PNI was predictive of a poor prognosis and was associated with clinicopathological features in patients with CRC, and the 41-45-58 four-stage division may be suitable for determining prognosis. PNI may thus provide an additional index for use along with the current TNM staging system to determine more accurate CRC prognoses.