A retrospective, population-based cohort study in JAMA Oncology found Black women in the United States were more likely to have a high-risk recurrence score and die of axillary node-negative breast cancer than non-Hispanic White women who had similar scores.
When comparing recurrence scores in the United States, investigators found that Black women were more likely to have a high-risk recurrence score and to die of axillary node-negative breast cancer than were non-Hispanic White women with comparable scores, according to data published in JAMA Oncology.
The research team explained that genomic assays for identifying candidates for adjuvant chemotherapy need to be calibrated for populations with greater racial/ethnic diversity because the Oncotype DX Breast Recurrence Score test currently has low prognostic accuracy in Black women.
“This study suggests that Black women in the [United States] with [estrogen receptor (ER)–]positive, ERBB2-negative, axillary lymph node-negative breast cancer are more likely to have a high-risk [recurrence score] and to experience breast cancer–specific mortality compared with non-Hispanic White women within the same risk group,” wrote the investigators, who were led by Kent F. Hoskins, MD. “In addition, the [recurrence score] provides less prognostic information for Black women.”
When focusing on recurrence scores, Black women were significantly more likely to have a score greater than 25 compared with non-Hispanic White women (17.7% vs 13.7%; P <.001). Moreover, the prognostic accuracy of the recurrence scores for Black women was significantly lower than the accuracy for non-Hispanic White women, with a C index in each group of 0.565 (95% CI, 0.592-0.720) and 0.700 (95% CI, 0.677-0.722), respectively (P = .002).
Risk models that adjusted for age, tumor characteristics, and treatment also found that Black women with axillary node-negative tumors saw higher breast cancer–specific mortality than non-Hispanic White women within each range of recurrence scores. By range, the hazard ratios for the comparison of the 2 groups were 2.54 (95% CI, 1.44-4.50) for those with recurrence scores of 0 to 10, 1.64 (95% CI, 1.23-2.18) for scores of 11 to 25, and 1.48 (95% CI, 1.10-1.98) for scores greater than 25.
The 86,033 patients with breast cancer (mean [SD] age, 57.6 [10.6] years) who had available Oncotype DX Breast Recurrence Score test information included 64,069 non-Hispanic White women (74.4%), 6719 non-Hispanic Black women (7.8%), 7944 Hispanic women (9.2%), 6950 Asian/Pacific Islander women (8.0%), and 351 American Indian/Alaska Native women (0.4%).
“The findings suggest that Black women disproportionately develop aggressive ER-positive tumors and that the Oncotype DX Breast Recurrence Score test incompletely defines prognosis in these women,” wrote the investigators. “Genomic prognostic assays may require recalibration for racial/ethnic minority groups. These factors could contribute to racial/ ethnic disparities in breast cancer mortality and require further study.”
The investigative team utilized the Surveillance, Epidemiology, and End Results (SEER) Oncotype DX 2004 to 2015 database to compile a cohort of women 18 years and older who were diagnosed with first primary stage I to III, ER-positive breast cancer in order to gather breast cancer–specific survival data. The primary end point was breast cancer–specific mortality as it relates to racial/ethnic groups.
Because the information for patients from the SEER registry was collected nonuniformly, the investigators stressed that there is a potential for bias in the study. More, the investigators explained that even though factors were adjusted for including age, tumor characteristics, and treatment, there is still a chance that factors not adjusted for could have impacted the results.
“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 the investigators.
Hoskins KF, Danciu OC, Ko NY, et al. Association of race/ethnicity and the 21-gene recurrence score with breast cancer–specific mortality among US women. JAMA Oncology. January 21, 2021. doi:10.1001/jamaoncol.2020.7320