Abstract IA07: Outcome disparities in multiple myeloma: The role of race/ethnicity
Authors: Ailawadhi Sikander 
Published: May 2016

Abstract
Approximately 27,000 new cases of multiple myeloma (MM) will be diagnosed and more than 11,000 deaths will occur from it in 2015. Overall, 5-year relative survival rates have improved from 26.5% in 1975 to 44.9% in 2010, and this has been attributed to the introduction of novel therapeutic agents, widespread utilization of autologous stem cell transplant (ASCT), and improvement in supportive care modalities. However, studies evaluating the role of race/ethnicity in MM have shown marked disparities in incidence and outcomes of MM among patients of different racial subgroups. Traditionally, it has been known that African-Americans (AA) have a higher incidence of MM than Whites and that it occurs in AA at a younger age. Despite this difference in incidence, AA patients are known to have a better overall survival (OS) than Whites. Recent population-based outcomes analyses of MM patients beyond just Whites and AA has shown that Asians have the best median OS, while Hispanics have the worst, in a population that is more representative of the current US racial/ethnic mix. Additionally, the cumulative survival benefit over time as per a recent report was most pronounced among Whites (1.3 years) and least among Asians (0.5 years), suggesting a possible differential access as well as utilization of therapeutic modalities. Thus, despite overall improvement in MM outcomes over years, racial disparities exist.
While majority of the data so far has reported the existence of these outcome disparities, a few reports have explored the potential causes of these differences. With regards to disease biology, there is some data suggesting that MM patients belonging to different races may have variability in the incidence of high-risk mutations, with AA MM patients having a lower incidence of such mutations, supporting the better OS seen in AA patients as compared to Whites. Another suggestion supporting differences in an interaction between biologic and environmental factors in MM patients is the variability in incidence of second primary malignancies in patients after they have developed MM, which may affect their outcome and OS. Other causes of outcome disparities may include a differential access to certain treatment options, especially more complex ones like stem cell transplants, as well as certain novel therapeutic agents that may depend on the patient's insurance payer status, which brings up differences in socioeconomic status, education level and barriers in accessing healthcare. It has also been reported recently that access to comprehensive cancer centers has benefitted Whites more than racial minorities. While access issues are being reported for MM patients belonging to different races, it has been suggested that outcome disparities by race are not noted in equal access healthcare systems. The potential shortcomings for these studies in equal access healthcare systems though, have been small size, mostly single-institution and focusing primarily on Whites and AA, without much representation yet of Hispanics and Asians, despite these two racial subgroups being the fastest growing ones in the US.
Outcome disparities in MM by patient race have been established. The factors affecting these outcome disparities may be complex and interrelated, making it difficult to identify specific factors that may be modifiable. Yet, it is important to explore outcome disparities and their potential causes, especially in large cohorts prospectively, so that healthcare resources may be utilized efficiently and furthermore, the disadvantaged population subgroups may be benefitted by targeted interventions.
Citation Format: Sikander Ailawadhi. Outcome disparities in multiple myeloma: The role of race/ethnicity. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr IA07.