Black women experience a higher proportion of aggressive breast cancers than white women, which may help explain racial disparities in mortality, study data showed.
“Breast cancer incidence is higher in young black women compared with young white women, and while 2010 [SEER] data showed that, across all ages, white women had higher incidence, recent data from the American Cancer Society suggest that overall incidence rates have converged,” Melissa A. Troester, PhD, MPH, of the department of epidemiology at Lineberger Comprehensive Cancer Center at University of North Carolina, Chapel Hill, and colleagues wrote. “This convergence could compound breast cancer mortality disparities. Mortality hazard rates among black women vary by subtype but are 20% to 150% higher relative to white women.”
The researchers used RNA expression-based PAM50 subtype and recurrence scores to classify 980 invasive breast cancers. Troester and colleagues compared white patients with black patients by molecular subtype — Luminal A, Luminal B, HER-2-enriched and Basal-like — and recurrence score, as well as by age, comparing 50 years and younger vs. older than 50 years.
Black women had a lower frequency of Luminal A cancer in both age groups than white women (black vs. white women: aged ≤ 50 years, 25.4% vs. 42.8%; aged > 50 years 33.6% vs. 52.1% white). However, black women in both age groups showed a higher frequency of all other subtypes than white women. Black patients appeared three times more likely to have Basal-like cancer (OR = 3.11; 95% CI, 2.22-4.37), 45% more likely to have Luminal B cancer (OR = 1.45; 95% CI, 1.02-2.06) and twice as likely to have HER-2-enriched cancer (OR = 2.04; 95% CI, 1.33-3.13).
Black women with hormone receptor-positive or HER-2-negative cancers had Luminal A subtype less frequently than white women, but had significantly higher recurrence scores.
“If you look at the group of basal-like breast cancers, the burden of this disease is much higher if you’re young and black,” Lisa A. Carey, MD, also of the Lineberger Comprehensive Cancer Center, said in a press release accompanying the study. “We believe this is playing a role in racial disparities in outcomes between young and old, and black and white women with breast cancer.”
The findings from the study presented opportunities to provide black patients with a high risk for recurrence with different treatment options, Troester said in the press release.
“We can do better to distinguish aggressive and indolent cancers if we use the genomic data that is becoming available,” Troester said. – by Andy Polhamus
Disclosures: The researchers report no relevant financial disclosures.