Page 36 - Wondergem

Chapter 2
indolent lymphoma (16) and their transformation (10), thresholds of 18F-FDG uptake (SUV) to detect transformation may be a function of the subtype.
In order to define the best discriminative tracer for the detection of transformation of FL, we performed a prospective study with a head to head comparison of 18F-FDG and 18F-FLT in a homogeneous patient group consisting of patients with FL and transformation of FL only. In addition to maximum tracer uptake the intra-patient variability of tracer uptake was determined as this parameter might be a more accurate indicator for transformation.
Materials and methods
Patients with untreated histologically proven FL and patients with histologically proven transformation of FL (TF) were eligible. FL patients underwent a biopsy to establish the diagnosis, defined according to the WHO classification 2008 and were included based on this histology. Since it is unethical to obtain a biopsy of all involved lymph nodes in FL patients to rule out histological transformation in every separate lymph node, we defined FL as: a pathologically proven diagnosis of FL in a lymph node, confirmed retrospectively by a clinical course fitting FL: no need for therapy for at least one year after inclusion in the study OR a complete remission (CR) or partial remission (PR) on CT scan after therapy for indolent lymphoma (i.e. therapy without anthracyclins) and a subsequent treatment-free period of more than three months. InTFpatientsabiopsywastakenbecauseofclinicalsymptomssuggestingtransformation (B symptoms, localized tumor mass growth or elevated LDH). Transformation was defined as (areas of) DLBCL in a biopsy obtained from a patient previously diagnosed with FL.
The treating haematologist was blinded to all data except for the staging results (qualitative assessment) of the 18F-FDG scan, in the context of standard patient care. Patients were included when they had at least one lymph node with a diameter of at least 2 cm (measured on CT scan or ultrasound). Patients were excluded if treatment was started before PET-CT or if they had (transformation of) other types of indolent NHLs than FL. In accordance with the Declaration of Helsinki, all patients gave written informed consent to participate in this single center study, which was approved by the institutional review board. This trial was registered in the Dutch trial register: NTR code 1487.
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