Prognostic nutritional index as a predictor of anastomotic leakage after rectal cancer surgery

Background and objectives Anastomotic leakage remains a major complication following rectal cancer surgery. Neoadjuvant therapy, while improving oncological outcomes, may negatively impact nutritional and immunological status. This study aimed to evaluate the predictive value of the Prognostic Nutritional Index (PNI) for anastomotic leakage in locally advanced rectal cancer patients treated with neoadjuvant therapy. Materials and methods This retrospective study included 123 patients with locally advanced rectal cancer who underwent neoadjuvant therapy followed by curative resection with primary anastomosis between 2018 and 2024. PNI was calculated using preoperative serum albumin and lymphocyte count. ROC curve analysis determined the optimal PNI cutoff value. Univariate and multivariate logistic regression analyses identified independent predictors of anastomotic leakage. Results Anastomotic leakage occurred in 19 patients (15.4%). The optimal PNI cutoff was 51.25 (AUC = 0.756, sensitivity 78.9%, specificity 67.3%). In multivariate analysis, PNI was an independent predictor of anastomotic leakage (OR = 0.809, 95% CI: 0.696–0.941, p = 0.006). Coronary artery disease ( p = 0.038) and intraoperative blood transfusion ( p = 0.001) were also identified as significant independent risk factors for anastomotic leakage. Conclusions Preoperative PNI is an independent predictor of anastomotic leakage in rectal cancer patients following neoadjuvant therapy. PNI may serve as a practical tool for preoperative risk stratification and guide clinical decision-making regarding nutritional optimization and surgical planning.