Study: Using PET more prominently could benefit cancer treatment

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Increasing the use of PET imaging in cancer care management could have considerable benefits to tracking treat success, according to a study published in the Feb. 2nd issue of the New England Journal of Medicine.

Co-author of the study Malik Juweid, MD, associate professor of radiology, University of Iowa Roy J. and Lucille A. Carver College of Medicine, states that one of the biggest challenges in current cancer care treatment is understanding immediately how effective a treatment is. Therefore, the study was born to determine if PET was in fact a good road to providing earlier and more accurate therapy assessment.

Earlier Juweid's research has already led to changes in how PET is used in cancer care, according to a University of Iowa release. In that research – published in July of last year in the Journal of Clinical Oncology (needs to be italicized because it is the title of a journal) – Juweid and his collaborators indicated that adding FDG-PET to the standard computer tomography (CT)-based assessment criteria made the predictions of treatment outcome much more accurate for aggressive non-Hodgkin's lymphoma. From these results, new international criteria will include PET as an essential ingredient in treating lymphoma.

"Basically, about half of patients were called partial or incomplete responders because CT found a residual mass after treatment despite lack of any other evidence of disease," said Juweid. "However, PET showed that the residual mass was scar tissue rather than viable tumor in more than half of these patients. These patients were, therefore, reassigned as complete responders, and we found that they did just as well as patients who had been given the 'all clear' from the CT scan."

The study showed that if the PET study is negative, patients can be safely observed without biopsy, and patients and physicians can be much more confidant that the patient will remain progression free. However, if a PET scan is positive and the findings are confirmed by a biopsy, patients can move more quickly to necessary salvage therapy.

PET is currently approved by the Centers for Medicare and Medicaid Services (CMS) for restaging in breast, colorectal, esophageal, head and neck, and non-small-cell lung cancers, as well as melanoma and lymphoma.

PET has a special place in monitoring tumor response, Juweid said, which can enable physicians to monitor tumor response during treatment and potentially to tailor the treatment based on the PET results.

As of right now, breast cancer is a CMS-approved clinical use for PET in monitoring response to treatment. However, Juweid said that based on research, PET could have a much broader application.

"For PET to be approved for monitoring treatment, clinical trials will need to demonstrate that using PET to tailor treatment has a beneficial effect in terms of patient outcomes," Juweid said.

He also believes that the idea of improved outcomes needs to be broadened.
For example, stopping chemotherapy when a PET scan shows the treatment is not working so that alternative treatment could be attempted.