Prognostic Impact of Absolute Lymphocyte Count/Absolute Monocyte Count Ratio and Prognostic Score in Patients with Nasal Type, Extranodal Natural Killer/T Cell Lymphoma

Nasal type, extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is a heterogeneous disorder with poor prognosis, requiring risk stratification in this population. We designed to investigate the prognostic significance of absolute lymphocyte count (ALC), absolute monocyte count (AMC), ALC/AMC ratio and ALC/AMC prognostic score (low risk, normal ALC and AMC; intermediate risk, low ALC or high AMC; high risk, low ALC and high AMC) and to determine whether ALC/AMC ratio or prognostic score is a better predictor of prognosis in ENKTL. A total of 264 patients with newly diagnosed ENKTL were retrospectively analyzed in present study. Receiver Operating Curve analysis showed that optimal cut-off values of ALC, AMC and ALC/AMC ratio were 1.0×10⁹/L, 0.5×10⁹/L and 2.85, respectively. In multivariate analysis all tested factors including ALC, AMC, ALC/AMC ratio and prognostic score were independent risk factors. After a median follow-up of 30 months (range 1-87), an estimated 3-year overall survival (OS) in the 264 patients was 75.4%. Patients with ALC/AMC ratio≥2.85 had a better OS and progression-free survival (PFS) than those with ALC/AMC ratio<2.85 at diagnosis (3-year OS rate: 83.4% versus 61.9%, P < 0.001; 3-year PFS rate: 76.5% versus 53.0%, P< 0.001). Significant difference has been noticed in the patients according to ALC/AMC prognostic score in 3-year OS (low risk vs. intermediate risk, 88.3% vs. 66.5%, p = 0.001; low risk vs. high risk, 88.3% vs. 0%, p < 0.001; intermediate risk vs. high risk, 66.5% vs. 0%, p = 0.001) and in 3-year PFS(low risk vs. intermediate risk, 80.7% vs. 58.3%, p = 0.002; low risk vs. high risk, 80.7% vs. 0%, p < 0.001; intermediate risk vs. high risk, 58.3% vs. 0%, p = 0.003) . The International Prognostic Index (IPI) and Korean Prognostic Index (KPI) were used for predicting these patients' prognosis, the result showed that the discrimination was not power. When applying ALC/AMC ratio and prognostic score to the IPI and KPI model, the latter showed a better discrimination as compared to the former.