Late-Onset Neutropenia After Rituximab-Containing Therapy for Non-Hodgkin Lymphoma

Background Late-onset neutropenia (LON) is a known adverse effect to rituximab therapy. Information about its real incidence and clinical implications comes from case reports and few retrospective studies specifically designed to study LON. However, large prospective studies of LON are lacking in the literature. We aimed to determine the incidence of LON in a group of non-Hodgkin lymphoma patients treated with rituximab and to analyze the clinical course, complications, and risk factors associated with LON. Patients and Methods We retrospectively reviewed 183 patients with a diagnosis of non-Hodgkin lymphoma consecutively treated with rituximab alone or in combination with chemotherapy. Results We identified 11 patients with grade 3/4 LON (13 episodes) out of 183 patients (6%). The median time to onset of LON was 75 days, and the median time to recovery from neutropenia was 100 days. The median neutrophil count nadir was 0.55 × 10 9 /L (range, 0.06-0.9 × 10 9 /L). Two patients presented infectious complications, one with fatal outcome. Conclusion In our experience, the incidence of recognized LON is low (6%), although its real incidence may be greater because of the asymptomatic course and quick recovery in most cases. Infectious complications are unusual, but life-threatening complications can emerge. A careful evaluation of all cases of LON is warranted.