AbstractBackgroundThis study aimed to evaluate the predictive value of systemic inflammation response index (SIRI) in primary gastrointestinal diffuse large B‐cell lymphoma (PGI‐DLBCL) patients and establish a highly discriminating risk prediction model.MethodsThis retrospective analysis included 153 PGI‐DCBCL patients diagnosed between 2011 and 2021. These patients were divided into a training set (n= 102) and a validation set (n= 51). Univariate and multivariate Cox regression analyses were conducted to examine the significance of variables on overall survival (OS) and progression‐free survival (PFS). An inflammation‐covered score system was established according to the multivariate results.ResultsThe presence of high pretreatment SIRI (≥1.34,p< 0.001) was significantly associated with poorer survival and identified as an independent prognostic factor. Compared with NCCN‐IPI, the prognostic and discriminatory capability of the novel model SIRI‐PI showed a more precise high‐risk assessment with a higher area under the curve (AUC) (0.916 vs 0.835) andC‐index (0.912 vs 0.836) for OS in the training cohort, and similar results were obtained in the validation cohort. Moreover, SIRI‐PI also showed good discriminative power for efficacy assessment. This new model identified patients at risk of developing severe gastrointestinal complications following chemotherapy.ConclusionsThe results of this analysis suggested that the pretreatment SIRI may be a potential candidate for identifying patients with a poor prognosis. And we established and validated a better‐performing clinical model, which facilitated the prognostic stratification of PGI‐DLBCL patients and can serve as a reference for clinical decision‐making.