A new study suggests that a person’s risk of progressing from a benign condition called monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma, a type of blood cancer, can change over time. On average, about 1% of people with MGUS go on to develop multiple myeloma each year. Doctors typically estimate a person’s risk of progressing soon after MGUS is diagnosed, using a test that measures the amounts of certain markers in the blood. That initial risk assessment guides how much follow-up care the patient receives. But according to the new findings, published July 18 in JAMA Oncology, the levels of those blood markers—and the risk of developing cancer—can change over time. “The study shows that most of the high-risk patients were low risk at some earlier point,” explained lead investigator Ola Landgren, M.D., Ph.D., professor of medicine and chief of the Myeloma Service at Memorial Sloan Kettering Cancer Center. “So, if you’re only going to do one test to determine risk, it’s probably not accurate,” he added. This is the first time that blood markers for MGUS progression have been prospectively and longitudinally tracked in people with the condition, noted co-lead investigator Jonathan Hofmann, Ph.D., M.P.H., of NCI’s Division of Cancer Epidemiology and Genetics. Further studies are needed to confirm these results, wrote Nikhil Munshi, M.D., of Dana-Farber Cancer Institute, and his colleagues in an accompanying editorialExit Disclaimer. But if confirmed, the results “would require rethinking” how people with MGUS are cared for, they wrote. Currently, only people who have a high- or intermediate-risk MGUS are recommended to receive annual follow-up tests to check for signs of progression. However, the study investigators said that their findings support annual blood tests for all individuals with MGUS, regardless of their initial risk assessment. To explore that idea further, Dr. Landgren and others have developed and initiated a large randomized clinical trial in Iceland to screen for MGUS among all Icelanders age 40 years or older, and to explore the benefits and harms of annual blood testing for people with MGUS.