A sub-analysis of a randomized phase 3 trial shows that non-Hispanic Black women with hormone receptor-positive, HER2-negative, lymph node-positive breast cancer had worse outcomes compared with non-Hispanic white patients, regardless of treatment and recurrence score. The findings from the RxPONDER study were presented today at the 2022 San Antonio Breast Cancer Symposium (SABCS) (Abstract GS1-01).
“Non-Hispanic Black women with hormone-positive, HER2-negative breast cancer, one to three positive lymph nodes, and a recurrence score of less than or equal to 25 have worse outcomes than non-Hispanic white women independent of recurrence score, treatment arm, age, and grade,” said Yara Abdou, MD, lead author of the study and an assistant professor at the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, at a news conference announcing the results.
Racial disparities in breast cancer persist, as Black women have a 4% lower incidence but 40% higher breast cancer mortality than white women.
The RxPONDER trial investigated the role of recurrence score in determining which patients with early breast cancer benefit from adjuvant chemotherapy. For this analysis of clinicopathologic characteristics, outcomes, and race, researchers included a total of 4,048 HR-positive, HER2- women with one to three positive lymph nodes. Of these patients, 70% were non-Hispanic white, 6.1% non-Hispanic Black, 15.1% Hispanic, 8% Asian, and 0.8% Native American or Pacific Islanders. All patients had an Oncotype DX recurrence score – which measures the expression level of a group of 21 genes to predict the risk of recurrence on a 0 to 100 scale – of 25 or less.
The five-year invasive disease-free survival rate was 87.2% for Black patients compared with 91.5% for white patients, 93.9% for Asian patients, and 91.4% for Hispanic patients. The five-year distant relapse-free survival rate, which is the time from surgery to the first distant recurrence, was 90.1% in Black patients and 94.7% in whites.
Researchers also found that 93% of Black patients accepted their treatment assignment compared with 86% of white patients. In addition, 98% of Black women remained on endocrine therapy at six months and 96% were still on it at 12 months, compared with 96.6% and 94.8%, respectively, for white patients. For Dr. Abdou, this suggests that outcome differences are not likely attributable to differences in treatment compliance within the first year, but longer follow-up research on the adherence after the first year is needed.
Dr. Abdou noted that definitive conclusions about racial differences in treatment cannot be made due to the small cohorts of minority patients and a limited number of events. Any data from the study should only be hypothesis-forming.
“This data definitely highlights that we need to do more in regard to diversity and inclusion in clinical trials, and the only way to overcome this is to build out racial cohorts in our clinical trials prospectively,” she said.
Understanding differences in patient biology is crucial, but it must go hand-in-hand with addressing the underlying factors that cause inequities, said Lori Pierce, MD, professor of radiation oncology at the University of Michigan Rogel Cancer Center in Ann Arbor. Dr. Pierce served as a discussant for the SABCS session in which the results were presented.
“Without a doubt, biology and ancestry are so very important, but we also have to dig deeper to understand and address the hidden factors of social determinants of health that contribute to disparities attributed to race. I think this is our collective responsibility, and I believe the onus is on us to do so,” she said.
The National Institutes of Health, National Cancer Institute, Susan G. Komen for the Cure Research Program, Hope Foundation for Cancer Research, Breast Cancer Research
Foundation, and Genomic Health (now Exact Sciences Corporation) provided funding for this study.
Dr. Abdou reported consulting relationships with AstraZeneca and Exact Sciences and honoraria from MJH holdings, MDEdge, and Clinical Care Oncology.
Dr. Pierce reported an unpaid consulting role with Exact Sciences.