Does screening mammography reduce disparities in care for TNBC?

An analysis of retrospective data from the Henry Ford Health System database shows that screening mammography that led to detection of triple-negative breast cancer (TNBC) resulted in similar outcomes for both white and African-American women. The findings suggest that the imaging is an important way to reduce disparities in breast cancer care.

Writing in a research letter in JAMA Surgery, the authors noted that African-American women have a significantly higher population-based breast cancer mortality rate and a disproportionately high burden of TNBC. The aim of their study was to determine the impact of screening mortality on those outcomes.

Methods
The data evaluated were from patients who self-identified as white or African-American and were diagnosed with nonmetastatic TNBC between January 2011 and December 2015. Participants were identified either through clinical symptoms or, if absent, through routinely scheduled mammography. All were followed up until death, loss to follow-up, or study termination on April 30, 2018.

The authors used Fisher exact and Χ² tests to compare categorical variables. All-cause survival was compared using log-rank test and P values. Multivariate Cox proportional hazards regression was used. Two-sided P values < .05 were considered significant.

Findings
There were no significant differences between the 68 white and 80 African-American women in age at diagnosis, tumor size, or nodal status and frequently of screening-detected disease also was similar. Invasive ductal tumors were the most common type seen in both groups (77% white women, 84% African-American). The African-American patients had higher body mass index (BMI) (32.2 kg/m² vs. 28.6 kg/m²; P = .001) but the women’s family histories were similar. 

More white than African-American patients were referred for genetic counseling (37.9% vs 21.7%; P = .03). Of the women, 88.6% who were white and 95.8% of those who were African-American had some form of nonpublic insurance.

Detection of TNBC though screening was associated with improved 4-year overall survival in African-American patients (screening-detected cases: 93.2% [95% CI, 87.0% - 99.9:]; non-screening detected cases, 59.1% [95% CI, 45.8% - 76.2%]; P <  .001) but not significantly improved in white patients (screening-detected cases: 87.5% [95% CI, 76.5% - 100%]; non-screening detected cases: 74.8% [95% CI, 62.3% - 89.7%]).

Conclusions
Univariate factors associated with better survival included screening-detected disease, non-T1 disease, and node positivity. Worse prognosis was associated with high-grade disease, lymphovascular invasion, and receiving adjuvant/neoadjuvant chemotherapy. Survival was not associated with race/ethnicity, age, histology, M1B1 status, BMI, insurance status, or parity.