SABCS 2018: TAILORx Results Show Association Between Clinical Outcomes in Breast Cancer and Race
An analysis of the association between clinical outcomes and race in participants enrolled in the TAILORx trial found that even with equivalent treatments among women with hormone receptor–positive, HER2-negative breast cancer, black women had worse clinical outcomes than white women, despite similar 21-gene assay recurrence score results and comparable systemic therapy. The findings add to a growing body of evidence suggesting a biologic basis or other factors contributing to racial disparities in hormone receptor–positive breast cancer. The study by Albain et al was presented at the 2018 San Antonio Breast Cancer Symposium (Abstract GS4-07).
Research Methodology
Results from the TAILORx phase III trial, which showed that most women (70%) with early-stage breast cancer do not benefit from chemotherapy and that treatment to prevent cancer recurrence with chemotherapy and hormone therapy following surgery is not more beneficial than hormone therapy alone in patients with a low or intermediate recurrence score, were published earlier this year in The New England Journal of Medicine. Following enrollment into the study, patients’ tumors were analyzed using a 21-gene Oncotype DX test and assigned a recurrence score of between 0 and 100. Patients with a low risk of recurrence (score of 0–10) were treated with hormone therapy alone, patients with a high risk (score of 26 and above) were treated with hormone therapy and chemotherapy, and patients with an intermediate risk (score of 11–25, the primary study group) were randomly assigned to receive hormone therapy and chemotherapy or hormone therapy alone.
The researchers’ analysis included 9,719 evaluable study participants to determine the association between clinical outcomes and race and ethnicity, in terms of invasive disease–free survival, distant relapse–free interval, relapse-free interval, and overall survival. Proportional hazards models were used for age (5 categories), tumor size (> 2 cm vs ≤ 2 cm), histologic grade (high vs medium vs low vs unknown), continuous recurrence score, race, and ethnicity in the overall population and randomized treatment arms in the cohort of women with recurrence scores of 11 to 25.
Of the 9,719 patients evaluated, 8,189 of the women were white, 693 were black, 405 were Asian, and 432 were of other or unknown race. Regarding ethnicity, 7,635 of the women were non-Hispanic, 889 were Hispanic, and 1,195 were of unknown ethnicity.
There was no significant difference in recurrence score distribution (P = 0.22) among blacks compared with whites or in terms of median (17 vs 17) or mean recurrence score (19.1 vs 18.2). There was likewise no difference in Hispanic vs non-Hispanic ethnicity for recurrence score distribution (P = 0.72) or median (17 vs 17) or mean recurrence score (18.5 vs 18.0). Black race (39% vs 30%) and Hispanic ethnicity (39% vs 30%) were both associated with younger age (≤ 50 years) at diagnosis.
The use and type of adjuvant chemotherapy and endocrine therapy, as well as the duration of endocrine therapy, were similar in black vs white and Hispanic vs non-Hispanic populations.
Study Results
In their analysis of the entire study population, the researchers found that black women had a 39% higher risk of breast cancer recurrence compared with white women and a 52% increased risk of death. About 68% of black women had a recurrence score of 11 to 25. In this intermediate group, there was an 80% higher risk of recurrence in black women compared with white women and a 67% higher risk of death in black women. When the researchers analyzed ethnicity, they found that Hispanic women generally had better outcomes than non-Hispanic women.
“In patients eligible and selected for participation in TAILORx, black women had worse clinical outcomes, despite similar 21-gene assay [recurrence score] results and comparable systemic therapy. This adds to an emerging body of evidence suggesting a biologic basis or other factors contributing to racial disparities in [hormone receptor–positive] breast cancer that requires further evaluation,” concluded the study authors.
Reasons for Disparities
“The racial disparities observed in this trial were not explained by differences in recurrence score, duration, or reported adherence to hormone therapy, nor were they explained by use of chemotherapy or characteristics such as age, tumor size, or tumor grade,” said lead author Kathy Albain, MD, Huizenga Family Endowed Chair in Oncology Research and Professor of Medicine at Loyola University Chicago Stritch School of Medicine, in a statement. “As such, our results suggest that biologic differences may contribute to the significantly different outcomes of black women compared to others with breast cancer.”
Disclosure: Funding for this study was provided by the National Cancer Institute. The study authors’ full disclosures may be found at sabcs.org.
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