Low absolute CD4+ T cell counts in peripheral blood: an independent predictor of inferior survival in natural killer/T-cell lymphoma—a retrospective cohort study

Background: Lymphopenia at diagnosis is considered a negative prognostic factor for patients with extra-nodal natural killer (NK)/T-cell lymphoma (ENKTL), especially that of the absolute cluster of differentiation 4+ T cell count (ACD4C), which has previously been identified as an independent prognostic factor in other hematologic malignancies. However, there is limited data available regarding the prognostic value of peripheral blood T lymphocyte subsets in ENKTL patients. The purpose of this study was to investigate the prognostic value of lymphocyte subsets, especially the ACD4C in ENKTL as a clinical biomarker.Methods: We analyzed the clinical data of 176 patients who met the inclusion criteria in Cancer Center of Integrated Hospital of Traditional Chinese Medicine, Southern Medical University from 2000 to 2018, including baseline clinical factors and ACD4C detected by flow cytometry, and examined the correlation between the results and clinical parameters and long-term outcomes.Results: The complete response rate of the high ACD4C group was 57.6%, which was significantly higher than that of the low ACD4C group (15.1%, P<0.001). The univariate analysis results showed that at a median follow-up time of 58.2 months, patients with a high ACD4C had significantly superior progression free survival (PFS) and overall survival (OS) (P=0.034 and P=0.001, respectively). The multivariate analysis results revealed that Eastern Cooperative Oncology Group performance status (ECOG PS) and the ACD4C were independent prognostic factors for OS [RR (95% CI): 2.288 (1.209-4.328), P=0.011 and RR (95% CI): 2.058 (1.070-3.968), P=0.031, respectively]. ECOG PS was also an independent prognostic factor for PFS [RR (95% CI): 1.858 (1.064-3.244), P=0.029], while ACD4C tended to be independently correlated with PFS (P=0.085).Conclusions: In this large cohort study, we found that the ACD4C was associated with survival outcomes in ENKTL patients. It is a potential biomarker, which may potentially be applied to clinical.