Prognostic Value of Double-expressor Phenotype and an Exploratory DEP-IPI Risk Model in Primary Testicular Diffuse Large B-cell Lymphoma: A Multicenter Retrospective Cohort Study.

INTRODUCTION: To evaluate the prognostic significance of double-expressor phenotype (DEP), International Prognostic Index (IPI) score, and treatment-related factors in patients with primary testicular diffuse large B-cell lymphoma (PT-DLBCL), and to explore a risk stratification model integrating DEP and IPI. PATIENTS AND METHODS: In this multicenter retrospective cohort study, 67 patients with PT-DLBCL treated at 3 tertiary hospitals in China between February 2013 and December 2024 were included. Clinical, pathological, and treatment-related data were collected from electronic medical records. Overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan-Meier method. Univariable and multivariable Cox regression analyses were performed to identify prognostic factors. Based on the independent predictors for OS, an exploratory DEP-IPI risk model was constructed. RESULTS: Among the 67 patients, DEP positivity was associated with significantly inferior OS and PFS, while patients with an IPI score ≥ 3 had significantly worse OS. In multivariable analysis, IPI score ≥ 3 (adjusted hazard ratio = 13.61, P = .042) and DEP positivity (adjusted hazard ratio =13.52,P = .005) remained independent adverse prognostic factors for OS. By contrast, no variable retained independent significance for PFS in the multivariable model. Contralateral testicular radiotherapy was associated with improved OS in Kaplan-Meier analysis but was not significant in Cox regression. Based on IPI and DEP status, patients were stratified into low-, intermediate-, and high-risk groups, which showed significantly different OS (P < .001). Treatment patterns did not differ significantly among the 3 risk groups. CONCLUSION: IPI score ≥ 3 and DEP positivity are independent adverse prognostic factors for OS in PT-DLBCL, whereas no variable retained independent significance for PFS in multivariable analysis. An exploratory DEP-IPI model may help identify clinically distinct risk groups and provide additional prognostic stratification. Further large-scale prospective studies are needed to validate its clinical utility.