The introduction of monoclonal antibody therapy has provided hope for the patients with follicular lymphoma (FL) that their prognosis may be improved. Rituximab (anti-CD20 chimeric monoclonal antibody, MabThera®) has proven to be highly effective and non-toxic targeted treatment of FL. The response rate and therapeutic benefit of monoclonal antibodies seems to be enhanced by the use of radioisotope-labelled antibody therapy. 90Y-ibritumomab tiuxetan (Zevalin®) was the first radioimmunotherapy (RIT) approved for the treatment in relapsed or refractory FL and many clinical trials demonstrated its efficacy and safety even in patients with advanced stage disease. According to new studies, RIT should be preferably used as consolidation treatment after tumor debulking. We report 3 patients with relapsed FL treated with four weekly doses of rituximab (375 mg/m2) and dexamethasone (20 mg/m2) with respect to their age, previous therapy, concomitant diseases or some concerns about chemotherapy complications. All patients responded to rituximab, but residual disease was demonstrated in each of them. Therefore, it was decided to treat them with 90Y-ibritumomab tiuxetan RIT in a dose of 14,8 MBq/kg in two patients and 11,1 MBq/kg in one patient (with platelet counts 125x109/l). Hematological nadirs were reached 4–6 weeks later, with one grade 3 neutropenia, one grade 4 and one grade 3 thrombocytopenia, respectively. Two patients had minor infection complications (acute bronchitis and enteritis). From 2 to 3 months after radioimmunotherapy, the 18F-fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) analysis proved no accumulation of 18F-FDG in any lymph node (LN) and computed tomography (CT) scans documented LN with the maximum size of 2x1 cm in two patients (one CR, two CRu). Eleven, nine and seven months after RIT, the patients were subjectively well, clinically in durable disease remission without any late complications

        Key words: folicullar lymphoma, 90Y-ibritumomab tiuxetan, rituximab, positron emission tomography, remission