Multiple Myeloma in Adolescent and Young Adults: An ASCO CancerLinQ and SEER Analysis

Background Multiple myeloma (MM) is exceedingly rare in adolescents and young adults (AYAs) < 45 years of age. Methods Real-world data from ASCO's CancerLinQ DiscoveryⓇ (CLQD) MM dataset and SEER were utilized to characterize demographics and outcomes of AYA MM patients in the United States in the modern treatment era. Frequencies of SPMs, VTEs, and infections were assessed, as were OS and cause of death. Results A total of 1946 AYA MM patients from SEER and 1334 from CancerLinQ were included. In terms of SPMs, AYAs were more likely to develop ALL (RR 2.6, P = .003) and AML (RR 1.7, P = .034), and less likely to develop nonmelanoma skin cancer (RR 0.2, P = .001) and prostate cancer (RR 0.1, P = .013) than MM patients ≥ 45. AYAs were at lower risk of VTE (RR 0.75, P = .002) and slightly higher risk of infections (RR 1.11, P = .002). Median OS among AYA MM patients was significantly longer than MM patients ≥ 45 in both datasets. In the SEER cohort, female sex (HR 0.74, P = .003), non-Hispanic ethnicity (HR 0.73, P = .005), and annual household income ≥ $65,000 per year (HR 0.67, P = .001) were associated with lower hazards of mortality. In the CLQD cohort, OS was significantly influenced by female sex (HR 0.6, P = .048). Race did not have a statistically significant impact OS in either cohort. Most AYAs died of MM (68.3%), other primary malignancy (7.5%, mostly leukemia), and cardiovascular events (5.2%). Infections accounted for 3.2% of deaths. Conclusion This analysis highlights some unique characteristics of AYA MM patients in the United States in the modern era.