African American patients with monoclonal gammopathy of undetermined significance (MGUS) were found to have lower risk of disease progression to multiple myeloma (MM) than white patients, according to findings from the SWOG S0120 trial.
MGUS is a precursor state to MM. Risk of MM has been shown to be higher among African Americans compared with white Americans. There is limited data on this population regarding disease progression from MGUS into MM.
“Current estimates of risk of progression of MGUS are based largely on studies in European American cohorts,” according to the study authors.
SWOG S0120 was a prospective observational trial of 331 patients with lgG/A monoclonal gammopathy. Of this cohort, 57 patients (17%) were African American. Disease progression was monitored for 5 years.
The investigators found that the risk of progression to clinical malignancy was significantly lower among African American patients compared with patients of other races and ethnicities. The 2-year risk of progression was 5% for African American patients, compared with 15% for the rest of the cohort. Risk at 5 years was 13% versus 24%, respectively (P=0.047). African American patients also had a lower proportion of high-risk gene expression profiles (GEP; 0% vs. 33%; P=0.01) and a higher average level of antibodies against Epstein-Barr virus (EBV; P<0.001), an infection that is associated with poor prognosis in patients with MM.
“These data provide the first prospective evidence that multiple myeloma precursor states in African American patients may have lower risk of disease compared with non-African American counterparts with lower incidence of high-risk GEP and increased EBV seropositivity. Race-dependent differences in biology and clinical risk of gammopathy may impact optimal management of these patients,” the researchers concluded.
This study was published in Clinical Cancer Research.