Second primary malignancy among older adults with multiple myeloma receiving first-line lenalidomide-based therapy: A population-based analysis.

OBJECTIVES

Clinical trials have suggested that patients with myeloma treated with lenalidomide may have an increased risk of second primary malignancies (SPM). Whether such risks are of significant relevance in the real-world clinical practice, particularly among older patients receiving first-line lenalidomide based therapy, remains unclear.

METHODS

Using Surveillance Epidemiology and End Results-Medicare database, we identified adults ≥ 65 years with plasma cell myeloma diagnosed in 2007-2015 who received at least one oral anti-myeloma agent. We defined first-line lenalidomide-containing therapy as use within 90 days of diagnosis. SPM was defined as a malignancy reported to a cancer registry > 90 days after myeloma diagnosis. We computed cumulative incidence of SPM (with death being a competing event) and compared SPM rates between patients treated with or without first-line lenalidomide using a Fine-Gray's model, adjusting for age, sex, race, ethnicity, prior malignancy, and histologic subtype.

RESULTS

Of 9850 Medicare beneficiaries, 4009 (41%) received first-line lenalidomide. During median follow up of 5.0 years, 423 patients (4.3%) developed SPM, including 361 solid tumors (85%) and 61 hematologic malignancies (14%). The cumulative incidence of any SPM at 5 years was similar among those who received first-line lenalidomide and those who did not (5.3% vs 4.4%; sub-hazard ratio, SHR 1.06, P = .53). Consistent results were seen in the risk of solid tumor (4.7% vs 3.6%; SHR 1.13, P = .24) or hematologic malignancy (4.7 vs 3.6%, SHR 0.73; P = .72).

CONCLUSION

First-line lenalidomide therapy among older adults with myeloma was not associated with a significantly increased risk of any SPM.