Background: Late-onset neutropenia (LON) has been reported following rituximab-containing chemotherapy. Its incidence and risk factors, however, have not been extensively studied.
Patients and methods: We retrospectively reviewed the medical records of 107 patients treated with rituximab-containing chemotherapy as a primary treatment of CD20-positive B-cell lymphomas and identified cases with LON as defined by the neutrophil count of <or=1.0 x 10(9)/l without an apparent cause after the recovery of neutrophil count following completion of the intended chemotherapy.
Results: With a median follow-up of 411 days, 23 patients developed LON out of the 107 at a median of 106 days after the last chemotherapy. Cumulative incidence of LON among the total patients was 24.9%. The median neutrophil count nadir was 0.61 x 10(9)/l. The LON episodes were generally self-limited, and filgrastim was administered in one patient. Including this patient, there were no serious infectious episodes in the cases with LON. In multivariate analysis, intensive chemotherapy regimens including high-dose therapy followed by autologous hematopoietic stem cell transplantation (ASCT) and high-dose methotrexate-containing regimens without ASCT were a risk factor for LON.
Conclusion: This study suggests that LON is a frequent complication of rituximab-containing intensive chemotherapy.