Racial Disparities in Autologous Stem Cell Transplant Utilization in Multiple Myeloma Persist Despite Referral to a Transplant Center

Introduction: Although the role of upfront autologous stem cell transplantation (ASCT) as an effective therapy for multiple myeloma (MM) is established in multiple clinical trials, it is well documented that non-Hispanic Black (NHB) and Hispanic individuals are less likely to receive ASCT for MM compared with age- and sex- matched non-Hispanic white (NHW) individuals.

Methods: We conducted an institutional review of new patient consultations for MM at the Froedtert and Medical College of Wisconsin Cancer Center from 1/1/2012 to 12/31/2022, a tertiary medical center in the state of Wisconsin. We looked at the ASCT utilization rate by race and studied factors related to patients undergoing ASCT, including univariate and multivariate analyses. We utilized a logistic regression model to examine the likelihood of receiving ASCT. We considered the following covariates in the model building process: age, race, sex, cytogenetics, ISS stage, renal co-morbidity, year of consult, time from diagnosis to consult. A significance level of 0.1 was used for entry into the model. Race was self-reported by patients in the medical record.

Results: We identified 1,221 MM consults from 2012 to 2022, of which 1,019 were NHW, 158 were NHB, and 44 were other minorities (“Other”) (Table 1). Median age at consult was 63, 66.1, and 61.8 years for NHBs, NHWs, and Other (p<0.1). All groups had similar cytogenetic risk, ISS staging, myeloma subtype, and time of diagnosis to consult. NHBs had longer median time from diagnosis to ASCT when compared to NHWs and Other, 6.4, 5.8, and 5.5 months, respectively (p=0.03). Median time from consult to ASCT was 4.3, 3.6, and 4.2 months for NHBs, NHWs, and Other (p=0.06). However, when comparing NHBs to NHWs, the difference between median time from consult to ASCT was significant (p=0.02). ASCT utilization rate was lowest in NHBs at 67.7% compared to Other at 72.7% and highest at 78.3% in NHWs (p=0.01) with trends over time shown in Figure 1. Multivariate analysis showed that NHWs were more likely to proceed to ASCT than NHBs (OR=2.698, 95% CI: 1.788-4.071, p=0.0021) while those with age ≥75 (OR=0.063, 95% CI: 0.044-0.09, p<.0001) and those with renal co-morbidity were less likely to proceed to ASCT (OR=0.523, 95% Cl: 0.36-0.761, p=0.0007).

Conclusion: Consistent with prior studies, NHBs were younger at the time of their MM transplant consultation and had a longer median time from diagnosis and consultation to ASCT when compared to NHWs. Despite referral to a transplant center, NHBs still had lower ASCT utilization than NHW, indicating that simply access to a transplant center is not the only barrier driving ASCT utilization differences between NHBs and NHWs. Age ≥75 years and renal comorbidity were also associated with lower ASCT utilization per multivariate analysis. Future plans to further understand the role of social determinants of health and the underlying role of structural racism on access to ASCT in multiple myeloma will help identify targets for interventions to eliminate these barriers.