Impact of Low Preoperative Prognostic Immune Nutritional Index on Survival and Postoperative Infectious Complications in Patients With Colorectal Cancer

Aim The prognostic immune nutritional index (PINI) is increasingly recognized for its potential clinical utility. However, multifaceted evaluations of its ability to predict oncological outcomes in colorectal cancer (CRC) and its association with postoperative infectious complications remain limited. Methods We analyzed the preoperative PINI in 487 patients with CRC who underwent surgical treatment between 2006 and 2015 to clarify its clinical relevance. Results A low preoperative PINI was significantly associated with several clinicopathological factors indicative of disease progression, including advanced pathological T category ( p < 0.001) and lymph node metastasis ( p = 0.001). It was an independent prognostic factor for disease‐free survival (DFS) (hazard ratio [HR]: 1.91; 95% confidence interval [CI]: 1.22–3.00; p = 0.005) and overall survival (OS) (HR: 2.51; 95% CI: 1.50–4.18; p < 0.001). A low preoperative PINI was also an independent risk factor for total infection (odds ratio [OR]: 1.82; 95% CI: 1.11–3.00; p = 0.02), encompassing all postoperative infectious complications. In a subgroup analysis of patients with stage III and high‐risk stage II CRC, a low preoperative PINI was an independent prognostic factor for both DFS (HR: 2.03; 95% CI: 1.24–3.32; p = 0.005) and OS (HR: 3.64; 95% CI: 1.61–8.19; p = 0.002). Additionally, propensity score matching analysis demonstrated that patients with a low preoperative PINI had significantly worse DFS ( p = 0.01) and OS ( p = 0.02). Conclusion The preoperative PINI is a valuable biomarker for both perioperative risk assessment and long‐term oncological management in patients with CRC.