Predictive effect of the systemic inflammation response index (SIRI) on the efficacy and prognosis of neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer

Background: Inflammation is a part of tumors, in which inflammatory cells can affect the proliferation, invasion, and development of tumor cells. More and more An increasing number of peripheral blood inflammatory markers have been found to play very important roles in the treatment and prognosis of cancer patients. The systemic inflammation response index (SIRI) is a newer inflammatory marker, and its role in colorectal cancer, especially in locally advanced rectal cancer, is still unclear. Methods From 2015 to 2020, 198 patients with locally advanced rectal cancer (LARC) who underwent surgery following neoadjuvant chemoradiotherapy (Neo-CRT) were analyzed. Patients were categorized into good and poor response groups according to their pathological results, and clinical characteristics and baseline parameters were compared between the two groups. The optimal cutoff values of inflammatory indicators were determined using receiver operating characteristic (ROC) analysis. Univariate analysis and multivariate analysis were performed using the Cox proportional hazard model. Survival analysis was calculated by the Kaplan‒Meier method. Result After the patients were grouped by good and poor responses, it was found that there were differences among the four indicators of CEA, neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and SIRI. In the ROC analysis, the NLR (P = 0.015), SII (P = 0.001), and SIRI (P = 0.029) were found to be significant prognostic factors. After univariate and multivariate analyses of the Cox proportional hazards regression model, only SIRI was found to be an independent prognostic factor for overall survival (OS) and disease-free survival (DFS). Finally, the Kaplan‒Meier survival curve also confirmed the predictive effect of SIRI on survival. Conclusion Preoperative SIRI can predict the response to Neo-CRT in patients with LARC and is an independent predictor of OS and DFS in postoperative patients. High SIRI was associated with poor radiotherapy response and predicted poor OS and DFS.