Page 47 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

Predictive value of interim PET in DLBCL
Study selection: Eligibility criteria
Patients
Adult patients treated with first-line immuno-chemotherapy regimens for stage I-IV DLBCL were considered as our target population. We excluded studies that investigated HIV-related lymphoma, central nervous system (CNS) lymphoma involvement, or post-transplant lymphoproliferative disease (PTLD). Studies containing less than 80% of DLBCL subtype were excluded, unless subgroup data for DLBCL were presented or if the remaining 20% had PMBCL or FL grade 3B [20]. Studies including ten patients or less were classified as case series and therefore also excluded.
Treatment procedures
Studies in which a change of treatment was based on the interim 18F-FDG PET result and prospective PET-adapted trials were not included. However, we allowed a change of therapy in patients with clinical evidence of progressive disease during first-line treatment [9]. We included all R-CHOP-like treatments as first-line treatment strategies [1,2,21–23], but we excluded studies if ≤50% of patients received rituximab.Therapies using other (new generation) monoclonal antibodies were excluded. Studies with autologous stem cell transplantation (ASCT) were eligible if this strategy was part of the preplanned first-line treatment. Radiotherapy was accepted if the decision to give radiotherapy was preplanned or used for consolidation of PET positive sites at the end of first-line treatment, but not affected by interim 18F-FDG PET results. If studies did not report on the use of ASCT or radiotherapy, we assumed that no ASCT or radiotherapy was given based on interim 18F-FDG PET result.
Interim 18F-FDG PET procedures
An interim 18F-FDG PET scan should have been performed after the first, second, third, or fourth treatment cycle. PET only as well as PET/CT systems were considered eligible. Use of other radiopharmaceuticals than 18F-FDG were not accepted. We focused on visual interpretation criteria only, as nowadays, semi-quantitative PET strategies are used for research purposes only and are not standard in the current guidelines yet [13]. PET response criteria were grouped into three categories: Deauville score (DS) on a 5-point scale [9,13], International Harmonization Project (IHP) [12], and custom visual criteria (i.e. not based on consensus guidelines).
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