African-American Multiple Myeloma Patients Have a Better Survival Than Caucasian Patients: a Population-Based Study Including 28,636 Patients.
Authors: Landgren Ola , Devesa Susan , Mink Pamela , Anderson William F , Weiss Brendan , Kristinsson Sigurdur Y , McGlynn Katherine 
Published: October 2019

Abstract
Abstract 1832
Poster Board I-858

Background
Multiple myeloma is the most common hematologic malignancy in African-Americans with twice the incidence of Caucasians. Prior single center studies have reported poorer survival among African-American multiple myeloma patients. In contrast, recent data based on multiple myeloma patients who received autologous transplantation in an equal access health care system, showed comparable survival between African-Americans and Caucasians, suggesting that the reportedly poorer outcome for African-Americans may be due to inequalities in access to care. Also, based on publicly available cancer registry data, several publications have reported excess mortality rates for African-American multiple myeloma patients. We conducted a large population-based study including almost 30,000 multiple myeloma patients to evaluate survival patterns by race. Methods. Patient information was obtained from the Surveillance, Epidemiology and End Results (SEER) cancer registries of the National Cancer Institute. Data were drawn from the original nine SEER registries (Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound, and Utah), which collectively cover approximately 10% of the U.S. population. Using the SEER*Stat statistical software package, we calculated 1-, 5-, and 10-year relative survival rates (RSR) of multiple myeloma patients diagnosed 1973-2004. We applied four calendar periods (1973-1979, 1980-1986, 1987-1993, and 1994-2004), follow-up through 2005 was included, and age at diagnosis was grouped into three strata (<50, 50-64, and 65+ years).

Results
We identified a total of 28,636 multiple myeloma patients (4,855 African-American; 23,781 Caucasian); 64% were 65 years or greater at diagnosis. When we included all patients, a comparison of survival rates in African-American and Caucasian males showed that African-American males had significantly better 5-year (32.2% vs. 28.7%) and 10-year (16.4% vs. 11.5%) RSRs (p<0.05). Similarly, African-American females had significantly better 1-year (73.3% vs. 70.2%) and 5-year (31.1% vs. 27.7%) RSRs than Caucasian females (p<0.05). When we examined survival patterns by calendar period (between 1973-1979 and 1994-2004), we found Caucasian patients to have significant improvements in the 1-year (from 67.1 to 72.4%), 5-year (from 24.1% to 31.7%), and 10-year RSR (from 9.9% to 14.9%). African-Americans also showed significantly improved 1-year RSRs (from 68.5% in 1973-1979 to 74.9% in 1994-2004) but the improvements in 5- and 10-year RSRs were not significant. When we examined survival patterns by age group, in the youngest age group (<50 years), both African-Americans and Caucasians improved 5- and 10-year RSRs, while 1-year RSR was improved for Caucasians only (from 80.9% to 84.9%). For patients 50-64 years, Caucasians had significantly improved 1-, 5-, and 10-year RSR; for African-Americans only 1-year RSR improvement was significant. Among patients 65+, there was no significant improved survival for African-Americans while Caucasians had improved 1-year (from 61.4% to 66.9%) and 5-year (from 19.6% to 24.7%) RSRs.

Conclusions
This large study of almost 30,000 patients found African-American multiple myeloma patients to have a significantly better prognosis than Caucasian patients, suggesting there is disease heterogeneity by race. After the introduction of newer therapies (autologous transplant, IMiDs, and bortezomib), Caucasian multiple myeloma patients showed a more pronounced survival benefit which might reflect inequalities in access to modern care; however, still African-Americans showed similar/better survival compared to Caucasians. Clinicians should be aware that the excess mortality rates for multiple myeloma among African-Americans, to a major degree, is a reflection of the fact that multiple myeloma is 2- to 3-fold more common among African-Americans. Future studies are needed to improve our understanding of the molecular basis for racial disparity patterns in multiple myeloma. Ultimately, such efforts will facilitate an improved understanding regarding disease subtype-specific benefits for individual agents, as well as mechanistic insights into drug sensitivity and resistance.

Disclosures
Weiss: The Binding Site, Inc.: Research Funding.