Breast Cancer Recurrence Score Less Accurate For Black Women

Author: By Lynda Williams, Senior medwireNews Reporter 

medwireNews: The Oncotype DX Breast Recurrence Score (RS) test is less accurate for Black women with node-negative breast cancer than for their non-Hispanic White counterparts, US researchers report. 

“This study found that Black women are more likely to have a high-risk RS and to die of axillary node–negative breast cancer compared with women of other race/ethnicity with the same RS”, report Kent Hoskins, from the University of Illinois at Chicago, and co-workers. 

“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 advise. 

The investigators collated information for 86,033 patients with a first primary stage I–III oestrogen receptor (ER)-positive breast cancer who were included in the Surveillance, Epidemiology, and End Results Oncotype DX 2004–2015 database.  

Most (85.6%) patients had axillary lymph node-negative disease; adjuvant chemotherapy was given to 4.8% of patients with a low-risk RS (0–10 points), 18.0% of patients with an intermediate RS (11–25 points) and 65.8% of patients with a high RS (>25 points). 

The majority (74.4%) of women were non-Hispanic White, while 7.8% were non-Hispanic Black, 9.2% were Hispanic, 8.0% were Asian or Pacific Islanders, and 0.4% were American Indian/Alaska Natives. 

Analysis indicated that Black women were significantly more likely to have a high-risk RS than their non-Hispanic White counterparts (17.7 vs 13.7%). This gave Black women a significant relative risk of 1.21 for this RS level after adjusting for age, year of diagnosis, tumour size and node status. And adjusting further for progesterone receptor (PR) status and tumour grade did not alter this association, the team remarks in JAMA Oncology. 

After a median 54 months of follow-up, risk of breast cancer-specific mortality (BCSM) from node-negative disease was significantly higher for Black women than non-Hispanic White women across all RS risk categories, after adjusting for age, year of diagnosis, PR status, tumour size, type of surgery and receipt of chemotherapy or radiotherapy. 

The hazard ratios for BCSM for Black versus non-Hispanic White women with low-, intermediate- and high-risk RS were 2.54, 1.64 and 1.48, respectively, and these did not change substantially after further adjusting for HER2 status. 

By contrast, there was no racial disparity identified for BCSM among women with node-positive disease, the researchers observe. 

Kent Hoskins et al found that competing risks analysis of the RS gave statistically significant prognostic information on BCSM for all racial/ethnic groups except Native Americans/Alaska Natives. 

However, Black women with a high-risk RS were 3.48 times more like to die from breast cancer than Black women with a low-risk RS, whereas this HR was 5.79 among non-Hispanic White women. 

And each 10-unit increase in RS provided significantly less prognostic information for Black women than their non-Hispanic White counterparts, with a subdistribution HR of 1.58 and a C index of 0.656 versus 1.71 and 0.700, respectively. 

“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”, the researchers summarise. 

“Genomic prognostic assays may require recalibration for racial/ethnic minority groups”, they suggest.  

Writing in an accompanying opinion, Joseph Sparano, from Montefiore Medical Center in New York, USA, and Otis Brawley, from the Johns Hopkins School of Medicine and The Bloomberg School of Public Health in Baltimore, Maryland, USA, discuss potential biological reasons for racial disparities in breast cancer. 

They note these include genetic susceptibility to taxane-induced neuropathy and socioeconomic-related differences in birthing habits and breast feeding, as well as tumour microenvironment differences that “may be influenced by socioeconomics and epigenetics”, prompting the commentators to suggest “that efforts focused on better understanding tumor and host factors in estrogen-dependent cancers may be prudent.” 

They continue: “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.” 

References 

Hoskins KF, Danciu OC, Ko NY, Calip GS. Association of race/ethnicity and the 21-gene recurrence score with breast cancer-specific mortality among US women. JAMA Oncol; Advance online publication 21 January 2021. doi:10.1001/jamaoncol.2020.7320  

Sparano JA, Brawley OW. Deconstructing racial and ethnic disparities in breast cancer. JAMA Oncol; Advance online publication 21 January 2021. doi:10.1001/jamaoncol.2020.7113