The standardized uptake value calculated from In-ibritumomab tiuxetan single-photon emission computed tomography/computed tomography is a useful predictor of the clinical response in patients treated by Y- ibritumomab tiuxetan therapy.

Y-Ibritumomab tiuxetan (IT) therapy is a radioimmunotherapy for indolent B-cell lymphoma. Several predictors of insufficient therapeutic effects have been reported. We performed a retrospective study at a single institute to investigate whether In SPECT/CT can predict the therapeutic effects and grade of cytopenia due to Y-IT therapy. We enrolled 16 consecutive patients who underwent Y-IT therapy, including 15 who underwent In-IT SPECT/CT. After Y-IT therapy, there were 4 patients in complete remission in whom the lesion SUV on In-IT SPECT/CT and soluble IL-2 receptor were significantly lower than those of the other patients (P<0.05 and P<0.05, respectively). Based on the log-rank test of factors associated with the progression-free survival (PFS), ≥2 previous treatment regimens was significantly associated with a poor prognosis (P<0.05). The SUV on In-IT SPECT/CT may be a good predictor of the clinical response to Y-IT therapy.