Zosia Chustecka

May 16, 2013

Standard care of patients with diffuse large B cell lymphoma who have completed treatment with immunochemotherapy includes routine monitoring with computed tomography (CT) every 6 months for 2 years, as well as regular physical examinations and blood tests.

The idea behind regular CT is that it will pick up any signs of relapse even when a patient is asymptomatic, and early detection of relapse allows earlier re-treatment.

But how useful is this regular imaging?

A new study from Mayo Clinic researchers, released yesterday, found that regular CT picked up very few relapses before clinical signs appeared.

The study followed 537 patients for a median of 59 months and found that 109 patients (20%) experienced a relapse. However, CT detected relapses before clinical signs had appeared in only 8 of the 537 patients (1.5%). Most relapses were detected by patient symptoms.

"Our results were surprising because the current standard of care is to include scans for the follow-up of this disease," said lead author Carrie Thompson, MD, a hematologist at the Mayo Clinic, Rochester, Minnesota. "We found that scans detected relapse in only a handful of patients who didn't have any of those other signs or symptoms."

Dr. Thompson will be presenting this study at the forthcoming annual meeting of the American Society of Clinical Oncology (ASCO), but she reported an outline of the findings at a premeeting presscast. She suggested that the study raises questions about the value of regular scanning and provides data for consideration in drawing up clinical guidelines on the management of these patients with diffuse large B cell lymphoma.

CT exposes patients to radiation, which theoretically increases the risk for a secondary cancer, and surveillance scanning can increase patient anxiety and lead to unnecessary biopsies, she said.

Not necessarily, said Izidore Lossos, MD, director of the lymphoma program and professor of medicine at the University of Miami, Florida. Some patients find it reassuring to undergo regular CT "because they want to know that they are okay," he told Medscape Medical News. He also pointed out that usually a finding on a CT scan would be investigated with positron-emission tomography (PET) before a biopsy is performed.

"This is a single study," Dr. Lossos emphasized. "There are other studies in the literature, and the data are controversial."

"Many of the relapses are found on physical examination after complaints from the patients, " he agreed "but this is not all patients."

The Mayo group reported that CT found relapses in only 1.5% of patients (8 relapses in 537 patients). But Dr. Lossos pointed out that CT detected 8 of the 109 relapses that occurred — which is nearly 10% of all relapses. "This is important," he suggested, particularly because these relapses were in patients who showed no signs and symptoms and so would have been missed on a physical examination.

"All in all, this is a very controversial point that has been discussed among experts already for a prolonged period of time, this question of whether we need to do follow-up CT scans or not," Dr. Lossos concluded. There is also another question, he said, of whether the detection of these relapses before patients exhibit any symptoms, and then starting treatment earlier, will lead to different outcomes in the long term. "There are no data on this at present."

"This is a very important study," said John P. Leonard, MD, professor of hematology and medical oncology and associate dean for clinical research at the Weill Cornell Medical College in New York City. "This work demonstrates that surveillance CT scanning is of low yield for asymptomatic patients with diffuse large B-cell lymphoma — the most common aggressive lymphoma — who have been in remission after therapy and are clinically well," he told Medscape Medical News.

"While the practice of 'routine scanning' is quite variable...there is no doubt that there are some situations when unneeded scans are performed," he added. "The potential downsides of excessive scanning of patients with aggressive lymphoma who are clinically well include expense, possible risks of unnecessary radiation exposure, additional testing and evaluations to pursue false-positive results, and the psychological stress on patients who have to deal with concerns about relapse."

"It is important that access to scanning is available to evaluate symptoms or clinical findings. [However], for most patients in remission from diffuse large B-cell lymphoma, a scan should probably not be 'automatically' performed at regular time intervals; instead, it should be driven by specific clinical concerns," Dr. Leonard explained.

There is a general trend within oncology to re-evaluate the usefulness of routine scanning, commented ASCO president-elect Clifford Hudis, MD.

Last year, routine CT in pediatric Hodgkin's lymphoma was questioned, and a leading expert in the field, James Armitage, MD, from the University of Nebraska Medical Center in Omaha, argued that routine surveillance imaging in patients with lymphoma carries potential risks and is costly. He also noted that many oncologists now own a CT scanner or a CT/PET scanner, which raises the issue of conflict of interest.

This research was supported in part by the National Cancer Institute.

2013 Annual Meeting of the American Society of Clinical Oncology (ASCO). Abstract 8504. To be presented June 1, 2013.

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