Survival Trends in Young Patients with Multiple Myeloma: Focus on Racial-Ethnic Minorities

Background: Population-based studies have shown outcome disparities in multiple myeloma (MM) patients by race-ethnicity. A definite improvement in overall survival (OS) as well as a trend towards younger age at diagnosis has been seen in MM over recent years. Hispanics and African-Americans (AA) have younger median age at MM diagnosis and while overall MM patients have had improving OS, a focus on younger patients, especially racial-ethnic minorities has been missing.

Methods: The Surveillance Epidemiology and End Results (SEER) 18 Registry data (1973-2014) was utilized for patients with a confirmed diagnosis of MM. Young MM patients were defined as being diagnosed at <40 years of age. Cases that received a diagnosis at death certificate or autopsy, no follow-up records, no documented age at diagnosis were excluded. OS was estimated using the Kaplan-Meier method. Survival curves were compared using log-rank tests. Expected survival was estimated using the age and sex specific death rates from the US population. Relative survival rate (RSR) was provided as the ratio of the observed to expected survival at individual time points. 5-year and 10-year RSR were calculated for patients diagnosed in 1995 or earlier (no novel agents or stem cell transplant; SCT), between 1996-2002 (SCT but no novel agents) and 2003 or later (SCT and novel agents) was calculated.

Results: A total of 89,451 MM patients with MM were available in the SEER database, of which 1,460 were diagnosed at ≤40 years of age (young MM) and met study inclusion. These included 59% males and 41% females with a median age at diagnosis 37 years (range 18-40) for the whole group. Median follow up for the whole cohort was 44 months (range: 0-419 months). Mutually exclusive racial subgroups included non-Hispanic Whites (NHW; 46.8%), non-Hispanic Blacks (NHB; 28.2%), Hispanic (18.4%), Asian (5.5%), Native American (<1%) and other (<1%). No significant differences were noted between the racial subgroups for median age at diagnosis, gender distribution or listed cause of death. Survival analyses were done between NHW, NHB and Hispanics, the 3 largest subgroups in the selected cohort. 5-year and 10-year RSR improved for patients age >40 years diagnosed in the 3 time periods for NHW, NHB and Hispanics (all p<.0001) as well as both genders (p<.0001). For the young MM patients there was a significant improvement in RSR noted over time for both genders (p<.0001) and among racial subgroups for NHW (p<.0001) and NHB (p<.0001) but not for Hispanics. Change in 5-year RSR for Hispanic young MM patients for the 3 time periods was 39%, 48% and 56% (p=.08) and for 10-year RSR was 21%, 35% and 33% (p=.13) (Figure 1).

Conclusions: There has been a significant improvement in median OS of MM patients over time due to availability of novel therapeutics including access to SCT. Racial disparities exist in outcomes and we show that young Hispanic MM patients have not yet realized a benefit in outcomes over time possibly due to variability in disease biology, response to therapy or access/utilization of the effective novel therapeutics. These factors need to be explored further to improve outcomes in all MM patients and eliminate disparities, especially the youngest subgroup of patients where survival, productivity and well-being carry different implications.

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