Post-neoadjuvant Prognostic Nutritional Index as a predictor of pathological response and survival in locally advanced rectal cancer.

e15632 Background: The response to neoadjuvant therapy in locally advanced rectal cancer (LARC) may be influenced by tumor and host-related characteristics, including nutritional and immune status. The prognostic nutritional index (PNI) has emerged as a potential biomarker; however, data on the prognostic value of post-neoadjuvant PNI in LARC remain limited. Methods: We performed a retrospective analysis of 240 patients with LARC who received neoadjuvant therapy from January 2018 to December 2023. The PNI was calculated post-neoadjuvant therapy 10 x serum albumin (g/dL) + 0.005 x total lymphocyte count (mm3). Pathologic complete response (pCR) was defined as a Ryan score of 0. To evaluate the association between PNI and pCR, a logistic regression model was employed. Overall survival (OS) and recurrence-free survival (RFS) were assessed using Kaplan-Meier analysis. Results: A cohort of 240 patients was included in the study, median age 58 years, gender distribution was comparable, lower rectum in 70% of cases and 72.5% presented positive lymph nodes. 59% received total neoadjuvant therapy (TNT) and 40% chemoradiotherapy (CRT). Following neoadjuvant therapy, 86% went to surgery, with a Ryan score of 0 in 27% of cases. The median post-neoadjuvant PNI was 45. The optimal PNI cutoff for discriminating OS was determined using the receiver operating characteristic (ROC) curve, yielding an area under the curve (AUC) of 0.681 (95% CI 0.584 to 0.778, p-value = 0.001). In multivariate analysis, a higher PNI remained independently associated with pCR (OR 1.10; 95% CI 1.02-1.19, p = 0.009). Patients with a PNI > 45 exhibited mproved RFS (mean RFS of 67.3 m vs 55 m; log-rank test, p = 0.031; median not reached) and OS (mean OS of 82.6 m vs 64.6 m; log-rank test, p = 0.002; median not reached, p = 0.002). Conclusions: Post-neoadjuvant PNI serves as an independent prognostic indicator for pathological response and is correlated with improved long-term outcomes in LARC. These findings underscore the importance of evaluating the nutritional and immunological status of patients with LARC, who may benefit from nutritional interventions. Univariate and multivariate analyses of factors for complete pathological response. Univariate analyses Multivariate analyses Factors OR 95% IC P value OR 95% IC P value Age 1.03 0.97 – 1.03 0.79 1.00 0.97 - 1.03 0.70 SexMaleFemale 10.78 0.41 – 1.50 0.46 10.83 0.42 – 1.66 0.60 Tumor grade123 0.511.221 0.12 – 2.190.51 – 2.93 0.360.64 0.591.281 0.12 – 2.760.49 – 3.32 0.500.60 Tumor siteLowerMiddleUpper 11.460.48 0.70 – 3.010.10 – 2.23 0.300.34 10.890.44 0.39 – 2.030.08 – 2.28 0.790.33 Lymph nodePositiveNegative 12.61 1.33 – 5.11 0.01 12.52 1.24 – 5.11 0.01 Neoadjuvant therapyTNTCRT 10.52 0.27 – 1.01 0.05 10.46 0.22 – 0.95 0.03 PNI 1.09 1.02 – 1.17 0.01 1.10 1.02 – 1.19 0.009 TNT: Total neoadjuvant therapy. CRT: Chemoradiotherapy. PNI: Prognostic Nutritional Index.