The prognostic significance of the prognostic nutritional index (PNI) and changes in (PNI) in rectal cancer patients receiving neoadjuvant chemoradiotherapy

Objective: The Prognostic Nutritional Index (PNI) has been widely used as a measure to reflect the immunological and nutritional status of cancer patients. Recent studies have identified changes in PNI values as a significant parameter. Our aim is to evaluate the relationship between pre-treatment PNI and post-treatment PNI changes with pathological complete response, disease-free survival, and hematological side effects caused by chemoradiotherapy in rectal cancer patients who received neoadjuvant chemoradiotherapy at the Akdeniz University Department of Medical Oncology. Method: Data from patients diagnosed with rectal cancer who received neoadjuvant chemoradiotherapy at the Akdeniz University Medical Oncology outpatient clinic between 2014 and 2021 were retrospectively analyzed. A total of 126 patients with complete data were included in the study. The PNI value was calculated using the formula PNI = [10 x serum albumin (g/dL)] + [0.005 x total lymphocyte count (per mm3)]. ΔPNI was defined as the difference between post-treatment PNI and pre-treatment PNI. Statistical analyses were performed using the SPSS (version 25) program. Survival analyses were conducted using the Log-Rank and Kaplan-Meier methods. ROC Curve analyses were conducted to evaluate the relationship between the cut-off point of PNI and disease-free survival with Pre-PNI, Post-PNI, and ΔPNI, and the results were compared. Results: Of the 126 patients included in the study, 81 (64.3%) were male and 45 (35.7%) were female, with a mean age at diagnosis of 59.83 years. According to ROC Curve Analyses, a high pre-PNI value was associated with a significantly higher survival rate (96.04%), a low post-PNI value was associated with a higher mortality rate (72%), and a high ΔPNI value was associated with a high survival rate (87.03%). Conclusion: Although PNI and changes in PNI are not related to hematological toxicity in rectal cancer patients, they are indicators of disease-free survival for rectal cancer. Patients with low ΔPNI, low pre-PNI, and low post-PNI values have a lower likelihood of survival. Key words: Rectal Cancer, Prognostic Nutritional Index, Prognostic Factors