No Racial Difference in Recurrence-Free Survival in HR+, HER2- Breast Cancer

The BluePrint (BP) and MammaPrint (MP) assays (procedures) determined that three-year recurrence-free survival (RFS; staying alive without cancer returning) rates were comparable, despite differing survival outcomes among Black and White patients with hormone receptor (HR)-positive, HER2-negative breast cancer, according to data presented at the 2023 San Antonio Breast Cancer Symposium.

Findings from a comparative study showed that Black women had a higher risk for basal-type tumors and luminal B tumors, when compared with White women. In Black women, 10.7% and 48.9% of tumors were basal-type and luminal B, respectively, compared to 6.0% and 39.3% among White women. Of note, low-risk, luminal A disease was more commonly observed in White women versus Black women.

Black patients experienced a three-year RFS rate of 93.6% as did White patients. Further distribution of patients for three-year RFS by MP and BP assays showed that White patients with luminal A, luminal B and basal-type breast cancer experienced three-year RFS rates of 97%, 90.6% and 80.6%, respectively. Black patients experienced three-year RFS rates of 96.7%, 92.5% and 88.9% in these respective disease types.

“MP and BP more precisely stratified tumors, resulting in distinct three- and 10-year outcomes independent of race and beyond clinical subtype alone,” lead study author Dr. Sonya Reid, assistant professor in the division of hematology/oncology at Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues, stated in a poster presentation of the data. “We identified racial differences in the distribution of MP and BP subtypes, but within each subtype, survival outcomes at three years were comparable between Black and White patients.”

This comparative analysis was conducted utilizing the 80-gene BP assay alongside MP, which is a 70-gene assay assessing the risk of distant recurrence. Both molecular subtyping assays are known to have prognostic value for patient outcomes on therapy.

MP was previously shown to aid treatment decision-making in the phase 3 EORTC 10041/BIG 3-04 MINDACT trial by accurately identifying patients with clinically high-risk, genomically low-risk tumors who are likely to experience substantial benefit from regimens not including chemotherapy, according to a study from The New England Journal of Medicine.

Additionally, prior use of BP revealed that HR-positive tumors designated as Basal Type exhibit heightened aggressiveness and tend to be higher grade, a study from the Journal of Clinical Oncology noted.

Although Black women are 41% more likely to die from breast cancer than White women, they remain underrepresented in clinical trials and population studies, according to data from the poster. Investigators conducted an analysis of three-year outcomes and distribution in Black and White women with HR-positive, HER2-negative breast cancer.

The analysis assessed the heightened prevalence of HR-positive/basal-type tumors that contributed toward disparities in long-term survival within this group of patients. The correlation between MP and BP and their impact on 10-year outcomes within a subset of Black women was also evaluated.

The study included adult patients with stage 1 to 3 HR-positive, HER2-negative breast cancer enrolled in the population-based BEST study between 2005 and 2015, as well as patients enrolled in the ongoing observational FLEX study.

A total of 139 Black patients from the BEST study and 429 patients from the FLEX study were included. These patients were matched with 568 White patients enrolled in FLEX, controlling for age, tumor size and nodal status.

Patients were categorized as either low risk or high risk according to MP analysis, and subsequently sub-classified as having luminal A, luminal B, HER2-type or basal-type disease with BP.

The primary endpoint of the study was three- and 10-year RFS. Secondary endpoints included 10-year overall survival (OS; length of time from diagnosis or the start of treatment when a patient stays alive). The median follow-up was 3 years for patients in the FLEX study and 10.1 years for patients in the BEST study.

Within the total population of 1136 patients, 38.1% were pre- or peri-menopausal (41.9% of Black women; 34.1% of White women), and 72.5% were lymph node–negative (72.5%; 72.5%). Most patients had intermediate-grade disease (46.4%; 57.0%), followed by low-grade (24.4%; 26.8%) and high-grade (29.2%; 16.2%) breast cancer.

An additional analysis of long-term survival outcomes from the BEST study demonstrated that Black patients experienced a 10-year RFS rate of 88.4% and a 10-year OS rate of 89%. Further distribution of patients revealed that 44 Black patients with luminal A tumors had the highest 10-year RFS and OS rates versus other tumor subtypes, at 97.7% and 100%, respectively.

There were 71 patients with luminal B breast cancer that had a 10-year RFS rate of 83.5% (and a 10-year OS rate of 83.5%. The 10-year RFS and OS rates were both 85.0% for Black patients with basal-type tumors, indicating that diverse patients may experience more equivalent outcomes when classified using these molecular subtyping assays simultaneously.

The 10-year RFS and OS also indicated that patients with low-risk, luminal A disease should potentially avoid overtreatment, regardless of race.

“More aggressive treatment can improve outcomes for (patients with HR-positive, basal-type tumors), as demonstrated by improved OS in (those who) achieved pathologic complete response,” investigators stated in the poster. “These data highlight the importance of genomic testing to help optimize treatment and reduce outcome disparities in Black women.”

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