Evaluation of the role of inflammatory blood markers in predicting the pathological response after neoadjuvant chemoradiation in patients with locally advanced rectal cancer.

Purpose: This study aimed to evaluate the role of inflammatory blood markers in predicting the pathological response rate after neoadjuvant chemoradiation (neo-CRT) in patients with locally advanced rectal cancer (LARC).

Materials and methods: In this prospective cohort study, we analyzed the data of patients with LARC who underwent neo-CRT and surgical removal of the rectal mass between 2020 and 2022 in a tertiary medical center. Patients were examined weekly during chemoradiation and neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune inflammation index (SII) were calculated from weekly laboratory data. Wilcoxon signed-ranks and logistic regression analysis were utilized to determine whether any laboratory parameters during different time point assessments or their relative changes could predict the tumor response based on a permanent pathology review.

Results: Thirty-four patients were recruited for the study. Eighteen patients (53%) achieved good pathologic response. Statistical analysis by Wilcoxon signed-ranks method indicated significant rises in NLR, PLR, MLR, and SII on weekly assessments during chemoradiation. Having an NLR over 3.21 during chemoradiation was correlated with the response on a Pearson chi-squared test (p = 0.04). Also, a significant correlation was found between the PLR ratio over 1.8 and the response (p = 0.02). NLR ratio over 1.82 marginally missed a significant correlation with the response (p = 0.13). On multivariate analysis, a PLR ratio over 1.8 showed a trend for response (odds ratio = 10.4; 95% confidence interval, 0.9-123; p = 0.06).

Conclusion: In this study, PLR ratio as an inflammatory marker showed a trend in the prediction of response in permanent pathology to neo-CRT.