Comparison of outcomes by race among a population-based matched sample of multiple myeloma patients

It is important to understand racial inequities in multiple myeloma treatment and survival, particularly in the Midwest where clear differences exist in cancer incidence and mortality. Since age and geographic location can greatly impact treatment and prognosis, matching patients on these characteristics can help identify reasons for outcome differences.

Retrospective data from the Iowa Cancer Registry’s Surveillance, Epidemiology, and End Results database were analyzed for adult patients diagnosed with first primary MM between 1/1/2010–12/31/2019. Matching procedures matched up to 4 White patients with each Black patient on age and city of residence. Demographic characteristics were compared, and Cox proportional hazards models were built to compare survival.

There were 1,845 patients in our overall sample, of which 85 were Black and 1,760 were White. There were 321 patients (74 Black, 247 White) that were matched. Black patients in the overall sample had decreased hazard for MM-specific death compared to White (HR = 0.50, 95% CI (0.43, 0.78)) when controlling for covariates. The decrease in MM-specific death in black patients was not statistically significant compared to matched controls (HR = 0.72, 95% CI (0.41, 1.27)). Treatment differences were not observed for either sample.

We found that, despite large racial differences in MM incidence and mortality in Iowa, there are no survival differences when matched on age and city of residence. These data fail to detect large barriers to myeloma treatment in Iowa, and are useful for formulating potential screening and prevention strategies. Future research should also assess results in different geographic areas, investigate survival among older White patients in rural areas, and investigate other potential reasons for mortality differences between Black and White MM patients such as specific treatments received.