EPIDEMIOLOGICAL LANDSCAPE OF YOUNG MULTIPLE MYELOMA PATIENTS DIAGNOSED EARLIER THAN 40 YEARS: THE FRENCH EXPERIENCE.

Multiple Myeloma (MM) is rare in young patients - especially before 40 years at diagnosis, representing less than 2% of all patients with MM. Little is known about the disease characteristics and prognosis of these patients. In this study we examined 214 patients diagnosed with MM ≤ 40 years old over 15 years, in the era of modern treatments. Among them, 189 patients had symptomatic MM. Disease characteristics were similar to older patients: 35% had anemia, 17% had renal impairment, and 13% hypercalcemia. The staging was ISS-1 in 52.4%, ISS-2 in 27.5% and ISS-3 in 20.1%. Overall, 18% of patients had high risk cytogenetics (del 17p and/or t(4;14)). Ninety percent of patients received intensive chemotherapy followed by autologous stem cell transplant, and 25% of patients had allogeneic stem cell transplantation predominantly at time of relapse. The median follow-up was 76 months, the estimated median overall survival was 14.5 years and the median PFS was 41 months. In multivariate analysis, bone lesions (HR=3.95; p=0.01), high ISS score (HR=2.14; p=0.03) and high-risk cytogenetics (HR=4.54; p<0.0001) were significant risk factors for poor outcomes. Among predefined time-dependent covariables, onset of progression (HR=13.2; p<0.0001) significantly shortened OS. At 5 years, Relative Survival compared to same age and sex matched individuals was 83.5%, and estimated Standardized Mortality Ratio was 69.9 (95%CI 52.7-91.1), confirming that MM dramatically shortens the survival of young patients despite an extended survival after diagnosis.