Rituximab and risk of second primary malignancies in patients with non-Hodgkin lymphoma: a systematic review and meta-analysis

Addition of the anti-CD20 monoclonal antibody rituximab to chemotherapy improves response rates and survival in patients with B-cell non-Hodgkin lymphoma (NHL). However, rituximab induces a transient B-cell depletion and a dose-dependent T-cell inactivation that could impair T-cell immunosurveillance. The impact of rituximab on second primary malignancy (SPM) risk remains unclear so far. We thus carried out a systematic review to compare SPM risk among patients treated or not with rituximab. We retrieved trials from MEDLINE and EMBASE and updated data presented at American Society of Hematology and American Society of Clinical Oncology meetings from 1998 to 2013. We selected randomized, controlled trials addressing newly or relapsed/progressive B-cell NHL in which randomization arms differed only from rituximab administration. Two authors extracted data and assessed the study quality. We analyzed nine trials involving 4621 patients. At a median follow-up of 73 months, a total of 169 SPMs were observed in patients randomized to rituximab compared with 165 SPMs in patients not randomized to rituximab (OR = 0.88; 95% CI 0.66-1.19). The proportion of females, histology subtypes, use of rituximab in first line or in maintenance did not influence SPM risk (P = 0.94, P = 0.80, P = 0.87, P = 0.87, respectively). Cumulative exposure through prolonged administration in trials with rituximab maintenance did not contribute to an increased risk of SPM (P = 0.86). Our meta-analysis suggests no SPM predisposition among NHL survivors exposed to rituximab at a median follow-up of 6 years