Guidelines Add PET for Evaluating Lymphoma Treatment

The guidelines will provide clinicians worldwide with uniform criteria to compare and interpret clinical trials of lymphoma treatments and should facilitate the development of new therapies.

The new guidelines, developed by the International Harmonization Project (IHP), build on criteria for treatment response assessment of non-Hodgkin's lymphoma published in 1999 by an international working group (IWG) of clinicians, radiologists, and pathologists.

Although the IWG criteria have been widely adopted by clinicians and regulatory agencies and used to approve several treatments, recent developments, including increased use of positron emission tomography (PET) scans and immunohistochemistry in lymphoma response assessment, prompted the IHP to considerably revise the criteria.

The IHP recommendations aim to standardize the parameters used in clinical trials for lymphoma and incorporate the new technologies. Furthermore, the revised guidelines encompass all lymphomas. The recommendations were published in the January 22, 2007, online issue of the Journal of Clinical Oncology. Bruce Cheson, M.D., professor of medicine at the Lombardi Comprehensive Cancer Center at Georgetown University Hospital (Georgetown, MD, USA), is senior author of the article and led the IHP effort.

Integration of PET represents a major change in the guidelines. Malik Juweid, M.D., associate professor of radiology at the University of Iowa (UI) Roy J. and Lucille A. Carver College of Medicine (Iowa, City, USA) and a member of the UI Holden Comprehensive Cancer Center, was co-chair of the IHP committee that developed the recommendations for performing and interpreting PET scans in response assessment of lymphoma. The imaging committee, which included world-renowned PET imaging experts from the United States, Europe, and Australia, was co-chaired by Dr. Sigrid Stroobants from University Hospital Gasthuisberg (Leuven, Belgium).

PET is a non-invasive imaging technique that uses radioactivity emitted from injected tracer chemicals to measure and image biologic activity. The most typically used PET radiotracer is fluorodeoxyglucose (FDG), a radiolabeled form of glucose, which is consumed more avidly by tumors than by healthy tissue.

Adoption of the revised guidelines is expected to have major implications for patient management, according to Dr. Juweid. "Many patients with either diffuse large B-cell lymphoma [DLBCL], which is the most common subtype of lymphoma, or Hodgkin's disease, who were previously considered in partial response to treatment based on the conventional assessment, will now be considered in complete response if their PET scan is negative. Such patients can be safely observed and are expected to have an excellent outcome.”




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University of Iowa Roy J. and Lucille A. Carver College of Medicine