New Study Points Out Flaw In Breast Cancer Test That May Impact Black Women

The NCCN Clinical Practice Guidelines in Oncology cites the test as a recommendation to determine treatment for patients with ER-positive, HER2-negative tumors without axillary lymph node metastases.

The validity of the most highly sought-after genetic test to assess breast cancer in the U.S. is under question as it relates to non-Hispanic Black women.

A recent study published in the Journal of the National Comprehensive Cancer Network shows that the Oncotype DX 21-gene test may underscore the chemotherapy benefits for Black women with estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer. The results of the research, led by the University of Illinois Chicago, also found an underestimation in younger cancer patients.

“This raises an important question regarding whether the 21-gene recurrence score has been adequately validated as a predictive biomarker in racial and ethnic minority patients,” wrote lead author Kent Hoskins, a professor of oncology at the University of Illinois Chicago, and colleagues. “Fewer than 10% of participants in the validation studies of the recurrence score were non-Hispanic Black, underscoring this concern.”

Specifically, the Oncotype DX Breast Recurrence Score Test “analyzes the activity of a group of genes that can affect how an early-stage breast cancer is likely to behave and respond to treatment,” according to breastcancer.org. The NCCN Clinical Practice Guidelines in Oncology recommends the test to determine treatment for patients with ER-positive, HER2-negative tumors without axillary lymph node metastases.

BEHIND THE STUDY

On the other hand, researchers at the University of Illinois Chicago used data of a total of 73,363 women who had ER-positive, HER2-negative breast cancer without axillary lymph node metastases. The study included 6,003 women who identified as Asian/Pacific Islander, 5,697 who were non-Hispanic Black, 6,688 who were Hispanic, and 54,945 who were non-Hispanic White. All women with a score of 26–100 had reductions in risk for death from their cancer, with chemotherapy treatment ranging from 20–50%, depending on ethnicity. Of the reductions, the study revealed that Black women aged 50 years or younger had a different risk than white women.

WHAT DO THE RESEARCHERS PROPOSE?

The researchers conducted an “exploratory subgroup” analysis of women aged 50 or younger with a reduction score of 11–25 and at least seven years of follow-up. As a result, it was proposed that the reduction cutoffs for chemotherapy should be adjusted in young women based on race/ethnicity,” especially Black women.

“If confirmed, the recurrence score cutoff for recommending adjuvant chemotherapy for young non-Hispanic Black women with ER-positive, axillary node–negative breast cancer may need to be lower than for other women. This study also underscores the need to account for the racial and ethnic diversity of the target population in the development and validation of cancer biomarkers,” conclude the authors.