In a separate interview, Andrew D. Zelenetz, MD, PhD, Chief of the Lymphoma Service at Memorial Sloan-Kettering Cancer Center in New York, said that he found the relapse rate of 20% observed in this study to be quite low, and he wanted to know the characteristics of the 537 patients included in the postsurveillance study.

Mayo Clinic hematologist Carrie A. Thompson, MD, the study’s lead author, said that those characteristics were available for the total cohort of 644 patients. She said that patients who entered post-treatment surveillance, by definition, had not had an early relapse and were not treatment-refractory. 

Dr. Zelenetz said that if the scan-detected relapse rate of 1.5% of relapses was  “true,” then routine post-treatment scans could be avoided in diffuse large B-cell lymphoma. “In our hands, about 80% of [diffuse large B-cell lymphoma] relapses are detected clinically and 20% by scans,” he noted.

Identifying Patients at Risk

“The present study is too small a dataset to try to identify a subgroup of patients who are at risk and in whom routine imaging would be useful. Patients with a negative scan don’t need imaging, but maybe patients with an equivocal scan do.  The risks associated with four scans in 2 years are quite low, and the study does not unequivocally suggest that imaging is not needed,” Dr. Zelenetz continued.

“To be conservative, the greatest risk of relapse in [diffuse large B-cell lymphoma] is within the first 2 years after treatment. It is not inappropriate to use routine imaging until we have more data,” he said.

The present study was a retrospective analysis. The ideal study to show whether imaging improves outcomes would be a prospective trial randomly assigning patients to two different follow-up regimens—one arm that includes imaging and one arm that doesn’t, he continued.

“This is a good study, and it is provocative. We need to continue to think about whether routine imaging is needed and, if so, in which patients,” Dr. Zelenetz said. ■

Disclosure: Drs. Zelenetz and Thompson reported no potential conflicts of interest.