Purpose: (18)F-fluoro-2-dexoy-D-glucose-positron emission tomography (FDG-PET)/computerised tomography (CT) has been used for staging and monitoring responses to treatment in patients with diffuse large B cell lymphoma (DLBCL). The sequential interim PET/CT was prospectively investigated to determine whether it provided additional prognostic information and could be a positive predictable value within patients with the same international prognostic index (IPI) after the use of rituximab in DLBCL.
Methods: One hundred and sixty-one patients with newly diagnosed DLBCL were enroled; the assessment of the PET/CT was performed at the time of diagnosis and mid-treatment of rituxibmab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R-CHOP).
Results: Sixty-seven patients (41.6%) presented with advanced stage disease and 27 (16.8%) had bulky lesions. Forty-three patients (26.7%) continued to have positive metabolic uptakes with a significantly high relapse rate (62.8%) compared to the patients with a negative interim PET/CT (12.1%) (P<0.01). After a median follow-up of 30.8months, the positivity of interim PET/CT was found to be a prognostic factor for both overall survival (OS) and progression-free survival (PFS), with a hazard ratio of 4.07 (2.62-6.32) and 5.46 (3.49-8.52), respectively. In the low-risk IPI group, the 3-year OS and PFS rates were significantly different in the patients with positive (53.3% and 52.5%) and negative (93.8% and 88.3%) interim PET/CT, respectively (P<0.01). These significant prognostic differences of interim PET/CT responses were consistent with the results of the patients with high-risk IPI group (P<0.01).
Conclusions: Interim PET/CT scanning had a significant predictive value for disease progression and survival of DLBCL in post-rituximab treatment; it might be the single most important determinant of clinical outcome in patients with the same IPI risk.
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