Peripheral blood CD8 + T-cell count at diagnosis predicts prognosis in R-CHOP-treated diffuse large B-cell lymphoma patients.

While the prognostic significance of peripheral blood (PB) lymphocyte counts in diffuse large B-cell lymphoma (DLBCL) patients treated with Rituximab, Cyclophosphamide, Doxorubicin Hydrochloride, Vincristine Sulfate, and Prednisone (R-CHOP) is established, the specific role of CD8+ T-cell counts (CD8c) remains unclear. Methods: This retrospective study analyzed 315 newly diagnosed DLBCL patients treated at Central Hospital of Xiangtan from January 2018 to September 2023. We evaluated the prognostic significance of initial CD8c and other clinical parameters using univariate and multivariate survival analyses to identify independent predictors of outcome. An optimal CD8c cut-off value of 264.5×106/L was identified. Low CD8c correlated with significantly improved 5-year progression-free survival (PFS) (88.78% vs 49.18%, p<0.001) and overall survival (OS) (84.02% vs 31.25%, p<0.001). Multivariate analysis confirmed CD8c as an independent prognostic factor for both PFS and OS. CD8c demonstrated significant interactions with lactate dehydrogenase levels. Notably, low CD8c groups consistently exhibited superior survival outcomes, even in the presence of other poor prognostic factors. Initial PB CD8c serves as an independent predictor for R-CHOP-treated DLBCL patients. These findings suggest CD8c may be a candidate for enhancing existing prognostic models, particularly when combined with established risk factors, underscoring the potential importance of host immune status in DLBCL prognosis and treatment outcomes. Independent validation in external cohorts is needed.