Does Race Impact Survival in Multiple Myeloma?

Purpose:

Multiple myeloma (MM), a cancer involving abnormal antibody production from plasma cells, accounts for approximately 1.8% of all new cancer cases in the US. The International Staging System (ISS) for MM classifies patients with serum beta2 microglobulin < 3.5mg/l and serum albumin ≥3.5g/dl as having stage I disease, patients with serum beta2 microglobulin ≥ 5.5 mg/l as having stage III disease, and all others as having stage II disease. The median survival by stage at time of diagnosis is 62 months, 45 months, and 29 months, respectively, for stages I, II, and III.

The median age at time of diagnosis of MM is 69 years, with approximately 62% of all patients being at least 65 years old at time of diagnosis. There is a 2-fold increase in MM incidence amongst blacks as compared to whites in both the male and female population. This study was conducted to further characterize our MM patient population and to potentially identify racial and gender impact on mortality.

Methods:

A retrospective chart review of all patients in our geographic region diagnosed with MM between 2012 and 2017 was conducted using the Louisiana Tumor Registry Board database. Clinical data abstraction included epidemiology, laboratory, and pathologic data at time of diagnosis, and time to autologous stem cell transplant and death, if applicable. We performed chi-square analysis, linear regression, and survival analysis to compare survival outcomes between groups.

Results:

Chart review data was available for 184 of the 243 patients diagnosed with MM between 2012-2017, including 89 (47.6%) males and 98 females (52.4%), and 90 (48.1%) whites and 88 (47.1%) blacks. Females were significantly older than males (66.1 vs 62.6 years, p=0.037) at time of diagnosis yet whites were not significantly older compared to blacks (65.1 vs. 63.9 years, p=0.498). Among the 108 patients with documented stage of disease, 17 (15.7%) patients were diagnosed with stage I MM compared to 40 patients (37.0%) diagnosed at stage II and 51 (47.2%) diagnosed at stage III. With regards to stage, there was no significant difference between race or sex in our population. When adjusted for gender and age at diagnosis, race was a significant predictor of survival time with survival being 6.45 months shorter for black patients with MM compared to whites with the disease. (95% CI, 1.1 to 11.8; p = 0.019)

Conclusion:

Our data suggest that race exists as an independent predictor of shorter survival in our black patient population with MM. Additional studies investigating the biologic diversity of this disease are warranted to explain this racial disparity.