That early warning sign is having certain B cells, called monoclonal B cells, in the blood, maybe even years before CLL is diagnosed.
In leukemia, which is a cancer of the blood, the body overproduces white blood cells, which don't mature properly and live much longer than normal. CLL is marked by too many B cells, note the National Cancer Institute's Ola Landgren, MD, PhD, and colleagues.
Landgren's team studied blood samples provided by 45 CLL patients up to six years before they knew their CLL diagnosis. The researchers ran two different tests on the blood samples, looking for monoclonal B cells.
All but one of the patients had monoclonal B cells in their pre-CLL blood samples, and 41 out of 45 had monoclonal B cells show up on both blood tests -- so monoclonal B cells could be a marker of future CLL.
"We found that the vast majority of patients with CLL have a precursor state from 6 months to 6 years before the development of clinically recognized leukemia," Landgren and colleagues write in The New England Journal of Medicine.
But the researchers aren't recommending routine blood tests to look for monoclonal B cells. The new study doesn't prove that having monoclonal B cells always leads to CLL, and more work is needed to learn how CLL develops and how those monoclonal B cells fit into that process.
Landgren's study is a "timely addition" that may help "open new doors to the detection, assessment, treatment, and prevention of B-cell lymphoid cancers," states an editorial published with the study. The editorialists included Robert Vogt Jr., PhD, of the CDC.