Risk of Secondary Malignancies After Multiple Myeloma: A Nationwide Case-Control Cohort Study

In light of improved survival rates among multiple myeloma (MM) survivors, we sought to assess their risk of secondary malignancies compared to the general population.

This nationwide population-based case-control cohort study utilized the Korea National Health Insurance Service (KNHIS) database incorporating data from 2009 to 2020. We analyzed a total of 7348 patients diagnosed with MM in the case cohort. We selected a control group of 29,351 individuals from the general population without MM, employing a 1:4 propensity score matching approach. Matching criteria included age, sex, and comorbidities to ensure a balanced and reliable comparison.

The cumulative incidence of any secondary malignancy was significantly higher in the case cohort than the control cohort (Hazard ratio [HR] 1.576, 95% confidence interval [CI], [1.381-1.798]). Hematologic malignancy risk was notably higher in the case cohort (HR 8.026, 95% CI, [5.402-11.924]), especially therapy-related myeloid neoplasms (t-MN) (HR 12.063, 95% CI, [6.839-21.278]). No significant difference was shown in nonhematologic malignancy incidence. In subgroup analysis, transplant-eligible MM patients had a significantly higher incidence of any secondary malignancy (HR 1.104, 95% CI, [1.003-1.214]) than transplant-ineligible patients. The incidence of secondary malignancy in MM patients in the lenalidomide-available era was not significantly increased compared to the prelenalidomide era.

While hematologic malignancies, particularly t-MN, are significantly elevated in MM patients compared to general population, nonhematologic malignancies do not appear to be significantly elevated.