Genomic Testing for Breast Cancer Shows Persistent Disparities for Black Women

Black woman with hair loss due to chemo.

Despite medical advances in breast cancer treatment and a general decline in mortality rates, significant racial disparities remain a critical issue in healthcare. A recent comprehensive review has examined how commonly used genomic tests—which help guide treatment decisions—may not fully account for these disparities between Black and White women with breast cancer.

What Are Genomic Tests?

Genomic tests analyze the activity of certain genes in cancer cells to help doctors understand how a tumor might behave and respond to treatment. These tests have become important tools for personalizing cancer care by helping determine:

• How likely cancer is to return after treatment

• Whether chemotherapy would be beneficial

• Which patients might safely avoid aggressive treatments

The three most common genomic tests examined in this review were:

1. Oncotype DX (21-gene signature): Helps determine if chemotherapy would benefit patients with early-stage breast cancer

2. MammaPrint (70-gene signature): Predicts risk of recurrence for early-stage breast cancer

3. PAM50 (50-gene signature): Classifies breast cancers into different subtypes with distinct prognoses

Researcher working with Genomic Testing

Key Findings: Disparities Persist Despite Testing

The research, led by Dr. Yara Abdou from the University of North Carolina at Chapel Hill, analyzed data from several major trials including TAILORx (with over 9,700 participants) and RxPONDER (with over 4,000 participants).

The results revealed troubling patterns:

More Aggressive Cancer Biology

Black women were more likely to have aggressive tumor types across all testing platforms:

• MammaPrint showed that 93% of Black women had high-risk tumors compared to 81% of White women

• PAM50 demonstrated that Black women were about three times more likely to have basal-like tumors (a particularly aggressive subtype)

Worse Outcomes Even Within Same Risk Groups

Even when grouped in the same risk category by genomic tests, Black women experienced:

• Higher recurrence rates: About 1.6-1.8 times higher risk of cancer returning

• Lower survival rates: About 1.5-1.7 times higher risk of death

• Less benefit from standard treatments: In the TAILORx trial, chemotherapy did not improve outcomes for Black women as it did for other groups

Why These Disparities Exist

The research shows that while genomic tests are valuable tools, they don't tell the complete story. The disparities appear to stem from a complex mix of factors:

Biological Differences

• Genetic factors that aren't captured by current testing

• Differences in how tumors develop and respond to treatment

Social Determinants of Health

• Access to quality healthcare

• Treatment delays

• Financial barriers

• Environmental exposures

• Chronic stress from systemic racism

Moving Forward: A More Complete Approach

According to the researchers, achieving equal outcomes for all breast cancer patients requires:

1. More inclusive research: Ensuring clinical trials include diverse populations

2. Integrated approach: Considering both genomic data AND social determinants of health

3. Equal access: Working to remove barriers to quality healthcare

4. Personalized care: Looking beyond genomic test results to consider the whole patient

What This Means For Patients

If you or someone you know is facing breast cancer:

• Talk with your doctor about how genomic test results apply to your specific situation

• Ask questions about all factors that might influence your treatment plan

• Seek out resources that can help address barriers to care

The bottom line is that while genomic tests provide valuable information for treatment decisions, they're just one piece of the puzzle. True progress requires considering both the biology of cancer and the social context in which it occurs.

By acknowledging these complexities, the medical community can work toward truly personalized care that addresses disparities and improves outcomes for all patients.

This study, led by Yara Abdou, MD, Division of Oncology, The University of North Carolina at Chapel Hill, was published online in JAMA Oncology.