Routine Imaging Costly in B-Cell Lymphoma but Rarely Picks Up Relapse After Remission

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Surveillance imaging of asymptomatic patients in first remission following treatment for diffuse large B-cell lymphoma offers little clinical benefit at substantial cost, according to Philadelphia researchers. Strategies utilizing 2 years of routine computed tomography (CT) or positron emission tomography (PET)/CT scans were associated with minimal survival benefit compared with follow-up without routine imaging.

“Surveillance imaging limited to 4 scans over 2 years is associated with significant aggregate costs,” said Scott F. Huntington, MD, an oncology fellow at Abramson Cancer Center, University of Pennsylvania, Philadelphia.

The goal of routine surveillance imaging is detection of early relapse, but “interestingly, there’s increasing data showing that the majority of patients who have diffuse large B-cell lymphoma who relapse will be symptomatic. So the utility of imaging is questioned,” he said.

He and colleagues created a decision-analytic Markov model and compared 3 surveillance strategies in 55-year-old patient cohorts: 1) standard follow-up without surveillance imaging; 2) routine follow-up with biannual CT scans for 2 years; or 3) routine follow-up with biannual PET/CT scans for 2 years.

The transition state model used 6-month length cycles with transition probabilities and clinical utilities derived from published studies. Costs were based on the Medicare fee schedule, and future cost/benefits were discounted at a rate of 3% annually.

The baseline model was biased to favor imaging strategies by associating asymptomatic imaging-detected relapses with improved clinical outcome, said Huntington. Quality-adjusted utility, lifetime costs, and incremental cost-effectiveness ratios were calculated for each follow-up strategy.

Conclusions were tested by multiway sensitivity analyses that varied the rate of asymptomatic relapse detection, likelihood of favorable International Prognostic Index (IPI) with asymptomatic relapse, and the impact of IPI on salvage therapy outcome.

“One trial found that patients with image-detected disease were more likely to have lower IPI scores, so they were basically having more favorable outcomes post-transplant,” he said. “The data from that trial was used to bias toward imaging.”

The benefit of imaging-based follow-up remained small after quality-of-life adjustments. Costs associated with imaging-based surveillance strategies are considerable, and incremental cost-effectiveness ratios were $202,300/quality-adjusted life-year (QALY) for CT strategies and $312,600/QALY for PET/CT strategies. Incremental cost-effectiveness ratios for imaging strategies remained >$100,000/QALY or were dominated by routine follow-up in multiway sensitivity analyses over clinically relevant ranges.

“The question is if routine surveillance imaging, or serial surveillance imaging, should be used, and there are providers who suggest against surveillance imaging,” Huntington said. “Certainly you want to see patients routinely, every 3 to 6 months, and perform a close history and physical exam because that is actually the majority of relapse—the patient is symptomatic. The patient may have changing symptoms or recurrent night sweats, and we may see new physical exam findings and new laboratory findings.”

“Usually, routine surveillance imaging is not picking up those relapses,” he said. “Even in the best case scenario for the utility of imaging, it’s still not likely to be cost effective.”

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