In lymphoma, FDG-PET is well established for staging and end-of-therapy response assessment. A promising more recent application is ‘early response assessment’, meaning that response to treatment is predicted using interim PET, i.e. PET during treatment. Timely assessment of forthcoming therapy failure in individual patients would have a profound impact on patient care by avoiding unnecessary toxicity and timely switching to potentially curative alternatives. Several observational studies have indicated that interim FDG-PET may be effective but inconsistencies prevail, especially in non-Hodgkin’s lymphoma (NHL). It is unclear to which extent these are due to differences in the timing of PET during therapy, different PET positivity criteria, different therapies and/or different subtypes of lymphoma. There is an urgent need to address these issues but this requires an integral approach using the results of various studies.


  • To build a PETRA database consisting of individual patient data (including PET scans) of the major international clinical studies on the value of interim-PET in lymphomas

  • To determine the optimal timing of interim FDG-PET during first-line therapy of diffuse large B-cell lymphoma (DLBCL)

  • To determine which interim FDG-PET response criteria perform best predicting end-of-therapy response rate and progression free survival at 2 years follow-up in patients with DLBCL

  • To assess whether and how chemo-immunotherapy affects the performance of interim FDG-PET

  • To assess whether and how type of NHL affects the performance of interim FDG-PET

  • To determine the cost-effectiveness of interim FDG-PET in DLBCL