Secondary multiple myeloma and antecedent cancer lineage.

Abstract

e22622 Background: The emergence of second primary malignancies (SPM) constitutes a growing clinical burden. However, data describing Multiple Myeloma (MM) as a subsequent malignancy remain limited. Emerging evidence suggests that the risk of developing secondary MM may vary according to the biologic lineage of the antecedent malignancy, however, these associations are understudied. We conducted a study to examine lineage-specific patterns in antecedent malignancies associated with secondary MM. Methods: We conducted a retrospective cohort study using the TriNetX US Collaborative Network. Adult patients who developed MM following a prior cancer diagnosis were identified. The index date was defined as the diagnosis of secondary MM. Demographics and prior malignancy distributions were summarized for the overall cohort. Comparative analyses were performed between patients with prior solid versus hematologic malignancies, and between prior myeloid versus lymphoid malignancies. Outcomes were assessed starting 1 day after the index. Propensity score matching (1:1) was performed for age, sex, race, ethnicity, and comorbidities where applicable. Risk and survival analyses excluded patients with outcomes prior to the analysis window. Results: The cohort included 7,838 patients with secondary MM, mean age of diagnosis of MM 68.4 +/- 13 years, and was predominantly male and white population. Survival probability at the end of 10 years was 46.9%. Antecedent malignancies included malignant neoplasms of lymphoid, hematopoietic and related tissue (28%), Myeloproliferative Neoplasms (12.3%), Myelodysplastic Syndrome (MDS) (10%). Solid neoplasms included breast (5%), gastrointestinal (5%), urinary tract (4%) and respiratory (4%). After propensity score matching, secondary MM was more common after antecedent hematologic compared to solid tumors (risk difference 0.956%, 95% CI 0.908-1.004%; OR 12.08, 95% CI 10.29-14.18; HR 12.44). In myeloid vs lymphoid malignancies, secondary MM occurred in 634 vs 419 patients, (risk difference 0.15%, 95% CI 0.105-0.193; OR 1.51, 95% CI 1.34-1.71, HR 1.51). Conclusions: Secondary MM was more commonly observed following antecedent hematologic malignancies, particularly myeloid neoplasms, than solid tumors in a large real-world cohort. This pattern highlights the need for heightened vigilance in long term survivors of myeloid neoplasms. Further studies should define mortality, disease risk features, and whether management strategies should differ from de novo MM. Characteristics of secondary multiple myeloma cohort. Demographic Characteristics Number of patients % of patients Secondary MM cohort 7,838 100 Male 4,213 54.58 Female 3,503 45.38 White 5,836 75.61 African American 1,109 14.37 Asian 181 2.35 Hispanic 303 3.93