New Guidelines for Assessing Lymphoma Treatment
An international team of cancer specialists and imaging experts, including Bruce Cheson, professor of medicine, head of hematology, and director of hematology research at Georgetown's Lombardi Comprehensive Cancer Center, has developed standardized guidelines for assessing how lymphomas respond to treatment. The guidelines will provide clinicians worldwide with consistent criteria to compare and interpret clinical trials of lymphoma treatments and should facilitate the development of new therapies. The recommendations appear in the Jan. 22 online issue of the Journal of Clinical Oncology.
"These revised guidelines will improve our ability to evaluate new treatments, to compare various treatments, and to provide a way for regulatory agencies, such as the FDA, to better evaluate new drugs," said Cheson. "The overall goal is to improve therapies for patients with lymphoma, which will lead to better outcomes."
The IHP recommendations aim to standardize the parameters used in clinical trials for lymphoma and incorporate the new technologies. In addition, the revised guidelines cover all lymphomas.
Cheson co-chaired the International Harmonization Project (IHP), a group of experts in the management of lymphomas who worked together to develop new guidelines for treatment. The IHP built upon existing guidelines for treatment response assessment of non-Hodgkin's lymphoma published in 1999 by Cheson and his colleagues. Although these guidelines have been widely adopted by clinicians and regulatory agencies and used to approve several treatments, recent advances, including increased use of positron emission tomography (PET) scans and immunohistochemistry in lymphoma response assessment, prompted the IHP to substantially revise the criteria.
Integration of PET represents a major change in the guidelines. PET is a non-invasive imaging technique that uses radioactivity emitted from injected tracer chemicals to measure and image biological activity. The most commonly used PET radiotracer is fluorodeoxyglucose (FDG), a radiolabeled form of glucose, which is consumed more avidly by tumors than by normal tissue.
In contrast to conventional computed tomography (CT) or magnetic resonance imaging (MRI), PET is able to distinguish between viable tumor and non-cancerous scar tissue that is often left behind after successful treatment of lymphoma. Incorporation of PET imaging into response assessment means that doctors can more accurately determine the nature of any residual mass and essentially rule out persistent cancer within the mass if the scan is PET-negative. This approach will allow researchers to accurately assess how well anti-lymphoma drugs work even when there is a residual mass at the tumor site following treatment.
The revised guidelines cover the use of PET for assessing all types of lymphoma. For two potentially curable types of lymphoma, DLBCL and Hodgkin's disease, the guidelines recommend that PET always be used to assess post-treatment response. PET also is strongly recommended prior to treatment to determine extent of disease for these lymphomas.
For the other 30 or so other subtypes of lymphoma, most of which are less common, the guidelines offer recommendations for when PET is useful and when it is not, and if PET is used in those cases, what criteria should be fulfilled.
The guidelines also address when a scan should be performed and recommend that PET obtained for response assessment at therapy conclusion be done preferably six to eight weeks after completion of chemotherapy and eight to twelve weeks after radiation. Timing is important because inflammation, which is present in the early weeks following treatment of the tumor, can cause false positive PET scans.
The Lombardi Comprehensive Cancer Center, part of Georgetown University Medical Center and Georgetown University Hospital, seeks to improve the diagnosis, treatment, and prevention of cancer through innovative basic and clinical research, patient care, community education and outreach, and the training of cancer specialists of the future.