Rituximab is not associated with increased risk of second primary malignancies in Israeli patients with diffuse large B cell lymphoma treated with RCHOP regimen

It is unknown whether rituximab increases the risk of second primary malignancies (SPMs) in patients with diffuse large cell B-cell lymphoma (DLBCL). We assessed SPMs in DLBCL patients diagnosed between 1996 and 2014 in comparison with the general Israeli population and dependent on rituximab treatment. Jewish patients had no increased risk for SPMs. Arab-DLBCL females had a higher SPMs rate compared to the general Arab-females population [SIR (95%CI) 1.86 (1.08–2.98)]. Incidence and time to SPMs, in both Jewish and Arab patients, were unaffected by rituximab. Risk for breast and thyroid cancers, in Arab and Jewish females respectively, were higher in the pre-rituximab era [SIR(95%CI) 5.25 (1.41–13.43) and SIR(95%CI) 3.85 (1.41–8.38), respectively]. Age ≥60 years was the only predictor for increased risk of SPM (HR = 2.5, p <.01). The increased risk of SPMs in specific subgroups of patients that were treated in the pre-rituximab era may reflect stringent medical surveillance employed in these populations.