A Letter to the Editor published in the American Journal of Hematology by Rong Wang, PhD, of Yale University, and colleagues is the “first study” to show smoldering multiple myeloma (SMM) incidence in the United States using cancer registry data. The authors reported on trends observed between 2012 and 2022.
Surveillance, Epidemiology, and End Results (SEER) data did not categorize and report on SMM separately from symptomatic MM until last year. This research team used data from the only known U.S. study with hospital registry data that identifies SMM separately from MM.
The team used the SEER data from 2012 to 2022 to categorize overall MM incidence into symptomatic MM, SMM, and other/unknown categories using pathology reports and clinicians’ statements.
During this timeframe, the overall incidence of MM was 6.72 per 100,000 person-years, representing a “significant increase” from 2012 to 2019 (P=0.03) and a “non-significant decrease” from 2019 to 2022 (P=0.08).
Mean incidence of SMM was 0.69 per 100,000 person-years, with a significant increase of 50% observed between 2012 and 2022. The researchers observed the following trends for SMM:
- The incidence increased with age through 75 to 79 years, then decreased after 80 years.
- Men had higher rates of SMM than women, particularly after the age of 60.
- Non-Hispanic Black populations had higher SMM incidence at all ages compared with non-Hispanic white and Hispanic populations.
- The increase in SMM incidence during the study period may be attributable to:
- Changes in administrative reporting and diagnosis criteria
- Evolving clinical management of SMM
- Growing prevalence of obesity
- Increased exposure to environmental and occupational hazards.
The study is limited by its use of registry data, which can lack necessary laboratory and clinical detail. In addition, SMM is often undiagnosed or underreported, thus the incidence of SMM could be higher than reported in this research.
“Our results could provide important insight when evaluating the impact of SMM management,” the authors concluded.
The research was supported by the National Cancer Institute.
Reference
Wang R, Davidoff AJ, Schoen M, et al. Trends in smoldering myeloma incidence in the United States from cancer registries, 2012–2022. Am J Hematol. 2026. Epub ahead of print. doi:10.1002/ajh.70202
