Black women also have a greater likelihood for aggressive ER-positive tumors, less well-defined prognosis

High-risk recurrence scores and higher breast cancer-specific mortality are more likely in Black women with estrogen receptor (ER)-positive, ERBB2-negative, axillary lymph node-negative breast cancer, according to a recent analysis of data from the Surveillance, Epidemiology, and End Results (SEER) Oncotype database. In addition, recurrence scores from the Oncotype DX Breast Recurrence Score test provided less prognostic information for Black women, suggesting that recurrence scores should be calibrated in populations that are more racially and ethnically diverse, researchers wrote in JAMA Oncology.

The Oncotype DX Breast Recurrence Score test—and the 21-gene recurrence score it provides—is the most commonly used genomic assay for prognostic information on the risks of distal recurrence and predictions of the likely benefits of adjuvant chemotherapy in women with ER-positive breast cancer.

“Given the widespread use of the 21-gene recurrence score for identifying candidates for adjuvant chemotherapy, it is important to examine the performance of the Oncotype DX Breast Recurrence Score test in diverse patient populations to validate this approach for tailoring treatment in women in racial/ethnic minority groups,” explained lead author Kent F. Hoskins, MD, of the University of Illinois at Chicago, Chicago, and colleagues.

They conducted this retrospective, population-based study to assess racial and ethnic disparities in breast cancer-specific mortality for women with hormone-dependent breast cancer across risk categories that were defined by the Oncotype DX Breast Recurrence Score test. In addition, Hoskins and fellow researchers sought to determine whether the prognostic accuracy of this 21-gene recurrence score varies according to race or ethnicity.

Hoskins and colleagues obtained breast cancer-specific survival data on 86,033 women (mean age: 57.6 years; 74.4% non-Hispanic White; 7.8% non-Hispanic Black) from the SEER Oncotype DX 2004-2015 database who were diagnosed with initial primary American Joint Committee on Cancer (AJCC) stage I to III estrogen receptor-positive breast cancer. All patients also underwent tumor testing via the Genomic Health Clinical Laboratory.

Univariate analysis showed that recurrence scores of >25 were more likely in Black women compared with non-Hispanic White women (17.7% versus 13.7%, respectively; P ˂ 0.001). Hoskins and fellow researchers also found that high-risk recurrence scores were also associated with age less than 40 years, larger tumor size, higher AJCC stage and tumor grade, and progesterone receptor-negative tumors. Upon unadjusted Poisson regression modeling, they also found that the relative risk for recurrence scores greater than 25 was 1.30 in Black women compared with non-Hispanic White women (95% CI: 1.23-1.37; P ˂ 0.001), and 1.21 (95% CI: 1.15-1.28; P ˂ 0.001) after adjustments were made for age, year of diagnosis, tumor size, and nodal status.

Across all risk groups, Black women had a significantly increased hazard of breast cancer-specific mortality compared with non-Hispanic White women. For example, breast cancer-specific mortality rates were higher for Black women with axillary node-negative tumors and recurrence scores of 0-10 compared with non-Hispanic White women with the same risk factors (subdistribution HR: 2.54; 95% CI: 1.44-4.50). Breast cancer-specific mortality rates were also higher for Black women with recurrence scores of 11-25 (subdistribution HR: 1.64; 95% CI: 1.23-2.18), and for Black women with scores greater than 25 (subdistribution HR: 1.48; 95% CI: 1.10-1.98).

Finally, Hoskins and colleagues found significantly lower prognostic accuracy of recurrence scores for Black women compared with non-Hispanic White women (C index: 0.656 versus 0.700, respectively; P=0.002). They noted that the confidence interval for the difference in C indexes did not cross zero (difference: -0.044; 95% CI: -0.085 to -0.002), a confirmation of significant racial and ethnic differences in the prognostic accuracy of the recurrence score.

“To our knowledge, this cohort study is the first population-based study using a nationally representative data set to compare breast cancer-specific mortality across racial/ethnic groups according to risk strata defined by the Oncotype DX assay,” wrote Hoskins and colleagues.

“This study found that Black women are more likely to have a high-risk [recurrence score] and to die of axillary node-negative breast cancer compared with women of other race/ethnicity with the same [recurrence score]. These findings also indicate that the validity of the Oncotype DX test for determining the need for adjuvant chemotherapy in Black women with node-negative tumors must be further investigated,” they concluded.

“There is no doubt that achieving equal care is necessary for achieving health equity for racial and ethnic minorities with breast cancer and other cancer types, but it may not be sufficient for some cancer types, including ER-positive breast cancer,” wrote Joseph A. Sparano, MD, of the Albert Einstein College of Medicine, Bronx, NY, and Otis W. Brawley, MD, of Johns Hopkins School of Medicine and The Bloomberg School of Public Health, Baltimore, MD, in their accompanying editorial.

“Designing biologically driven, evidence-based clinical trials focused on racial disparities represents one such strategy. Greater representation of racial and ethnic minorities in prospective clinical trials, and population-based cohorts, linked to robust socioeconomic data and biospecimens, represents another approach that will provide the tools necessary to deconstruct racial and ethnic disparities in breast cancer and other cancers where disparities exist,” they concluded.

Study limitations include the short follow-up (54 months), non-uniform treatment of patients in the SEER registry, lack of data on social determinants of health and on patient adherence to endocrine therapy, and the failure to adjust for factors not included in modeling that may have affected recommendations for Oncotype DX testing.

  1. Black women are more likely to have high risk recurrence scores and die of axillary node-negative breast cancer compared with non-Hispanic White women.

  2. This is the first population-based study to compare breast cancer-specific mortality across racial and ethnic groups according to risk strata defined by the Oncotype DX assay.

E.C. Meszaros, Contributing Writer, BreakingMED™

This study was supported by the National Center for Advancing Translational Sciences, National Institutes of Health.

Hoskins has received support from the University of Illinois at Chicago, and nonfinancial support from Pfizer Inc. outside of this work.

Sparano has received grants from the National Cancer Institute, and Brawley has consulted for Genentech on clinical trials inclusion.

Cat ID: 22

Topic ID: 78,22,585,730,22,691,192,925