Peripheral blood absolute lymphocyte/monocyte ratio as a useful prognostic factor in diffuse large B-cell lymphoma in the rituximab era

Objectives The tumor microenvironment, including tumor-infiltrating lymphocytes and myeloid-derived cells, is an important factor in the pathogenesis and clinical behavior of malignant lymphoma. However, the prognostic significance of peripheral lymphocytes and monocytes in lymphoma remains unclear. Methods We evaluated the prognostic impact of the absolute lymphocyte count (ALC), absolute monocyte count (AMC), and lymphocyte/monocyte ratio (LMR) in 359 diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Results The median follow-up time of the surviving patients was 58 months. Low ALC and an elevated AMC were both associated with poor survival rates. Receiver operating characteristic curve analysis showed that LMR was the best predictor of survival, with 4.0 as the cutoff point. Patients with LMR ≤4.0 were more likely to have an aggressive tumor, and this was associated with poor treatment responses. Patients with LMR ≤4.0 at diagnosis had significantly poorer overall survival (OS) and progression-free survival (PFS) than those with LMR >4.0. Multivariate analysis, which included prognostic factors of the International Prognostic Index, showed LMR ≤4.0 to be an independent predictor for the OS (hazard ratio [HR], 2.507; 95% confidence interval [CI], 1.255–5.007; P = 0.009) and PFS (HR, 2.063; 95% CI, 1.249–3.408; P = 0.005). Conclusions The LMR at diagnosis, as a simple index which reflects host systemic immunity, predicts clinical outcomes in DLBCL patients treated with R-CHOP.