Clinical presentation, progression, and outcome of patients with Clonal B-cell counts of less than 5 × 10⁹/L, 5 to 10 × 10⁹/L, and more than 10 × 10⁹/L and chronic lymphocytic leukemia immunophenotype

Objectives: The flow cytometric evaluation of peripheral lymphocytosis has led to a dramatic increase in the diagnosis of early stage chronic lymphocytic leukemia (CLL) and monoclonal B-cell lymphocytosis (MBL). Few studies exist to better delineate the natural history and differences between MBL and CLL. Methods: Applying the recently updated B-lymphocyte threshold of 5 × 10⁹ B lymphocytes/L for the diagnosis of CLL, we evaluated the differences in initial presentation, disease progression, time to treatment (TTT), and 10-year overall survival rates between patients with less than 5 × 10 × 10⁹/L, 5 to 10 × 10⁹/L, and more than 10 × 10⁹/L B cells. These clinical/treatment parameters were also compared among the MBL, 5 to 10 CLL Rai stage 0, and more than 10 CLL Rai stage 0 groups. Results: In total, 310 patients were included, with 67 in the less than 5, 75 in the 5 to 10, and 168 in the more than 10 B-cell groups. Statistically significant differences were seen when comparing the 5 to 10 and more than 10 B-cell groups regarding anemia (P = .021 for median hemoglobin; P = .028 for anemia <11 g/dL), platelet count (P = .041 for median platelet count), splenomegaly (P = .013), initial management plan (P = .012 for observation; P = .0021 for treatment with chemotherapy), and TTT (P = .0033). No statistically significant difference was seen among the MBL, 5 to 10, and more than 10 CLL Rai stage 0 groups regarding TTT and 10-year overall survival. Conclusions: Findings suggest that patients with B-cell counts of 5 to 10 × 10⁹/L behave clinically more similar to patients with B-cell counts of less than 5 × 10⁹/L.