Breast cancer is the most common cancer in women in the United States and worldwide. Furthermore, hormone-receptor–positive, axillary node–negative disease accounts for approximately half of all cases of breast cancer in the United States. 
Undated study results from the Trial Assigning IndividuaLized Options for TReatment or TAILORx study show that even with equivalent treatments in women with hormone receptor-positive, HER2-negative breast cancer, black women had significantly higher breast cancer recurrence and increased overall mortality compared to white women in a large phase III clinical trial.
Findings released from the federally funded TAILORx study, presented in June 2018, showed that most women with hormone receptor-positive, HER2-negative, axillary node-negative early-stage breast cancer did not benefit from chemotherapy.
On average, half of all breast cancers are hormone receptor-positive, HER2-negative, and axillary node-negative. The TAILORx study shows that chemotherapy may be avoided in about 70% of these women when its use is guided by the test, thus limiting chemotherapy to the 30% who we can predict will benefit from it.
“[The TAILORx study, would never have happened without federal funding for cancer research [and I expect that the results] will transform care immediately, and for the better. These data provide critical reassurance to doctors and patients that they can use genomic information to make better treatment decisions in women with early-stage breast cancer. Practically speaking, this means that thousands of women will be able to avoid chemotherapy, with all of its side effects, while still achieving excellent long-term outcomes,” noted Harold Burstein, MD, PhD, FASCO, at the time of the release of the study data during the annual meeting if the American Society of Clinical Oncology (ASCO) in June 2018.
The updated data of the study, which included a statistical analyses about the impact of ethnicity, were presented at the San Antonio Breast Cancer Symposium (SABCS), held December 4–8, 2018.
TAILORx was sponsored by the National Cancer Institute, part of the National Institutes of Health. It was designed and led by the ECOG-ACRIN Cancer Research Group. The study was, in part, supported in part by the Breast Cancer Research Foundation, Susan G. Komen, and the United States Postal Service (USPS) Breast Cancer Research Stamp.
“Our findings are consistent with prior studies indicating that black women with hormone-receptor positive, HER2-negative breast cancer have worse prognoses than women of other racial and ethnic backgrounds, even when they have access to the same contemporary cancer care,” said Kathy S. Albain, MD, FACP, FASCO, Huizenga Family Endowed Chair in Oncology Research and professor of medicine at Loyola University Chicago Stritch School of Medicine and director of the Breast and Thoracic Oncology Programs at the Cardinal Bernardin Cancer Center of Loyola Medicine in Maywood, Illinois.
“This suggests that additional research is required to determine the basis for these racial disparities and also highlights the need to enhance accrual of minority populations in cancer clinical trials.”
Albain and colleagues analyzed the association between clinical outcomes and race in participants from the TAILORx trial, which evaluated more than 10,000 women with the most common type of early breast cancer (hormone receptor-positive, HER2-negative, axillary lymph node-negative).
Following enrollment in the TAILORx trial, patients’ tumors were analyzed using the 21-gene Oncotype DX recurrence score test from Genomic Health (RS; on a scale of 0-100) which predicts cancer recurrence. Oncotype DX is one of several commercially available gene-expression assays that provide prognostic information in hormone-receptor–positive breast cancer. However, in addition to prognostic information, Oncotype DX also predicts who is going to benefit from chemotherapy treatment. Furthermore, the test looks at the unique biology of a patient’s tumor, allowing physicians to better personalize a treatment plan for each patient’s unique situation.
Patients with low risk (RS score of 0-10) were treated with hormone therapy alone, while patients with high risk (RS score 26 and above) were treated with hormone therapy and chemotherapy.
Patients with an intermediate risk of recurrence (RS score of 11-25)—the primary study group—were randomized to receive hormone therapy and chemotherapy or hormone therapy alone.
Of the 9,719 breast cancer patients able to be evaluated, 8,189 (84%) were white, 693 (7%) were black, 405 (4%) were Asian, and 432 (4%) were of other or unknown race. In terms of ethnicity, 7,635 (79%) were non-Hispanic, 889 (9%) were Hispanic, and 1,195 (12%) were of unknown ethnicity. The trial showed no significant difference in RS distribution or mean RS between white and black participants.
Usage and type of chemotherapy following surgery were similar between black and white participants and between Hispanic and non-Hispanic populations. Additionally, the usage, type, and duration of hormone therapy were similar between black and white participants and between Hispanic and non-Hispanic populations.
In an analysis of the entire trial population, black women had up to a 4% higher absolute risk of recurrence or death. When the authors compared outcomes between black and white women, they found that black women had a 39% higher relative risk of breast cancer recurrence and a 52% higher relative risk of death.
Sixty-eight percent of black women in the trial had a RS score of 11-25. In this intermediate group, there was an 80% higher relative risk of recurrence in black women compared to white women. There was a 67% higher relative risk of death in black women compared to white women.
When ethnicity was examined, women of Hispanic ethnicity generally had better outcomes than non-Hispanic women, Albain noted.
“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,” Albain said.
“As such, our results suggest that biological differences may contribute to the significantly different outcomes of black women compared to others with breast cancer.”
Limitations of the study include the retrospective nature of the analysis, lack of adequate power to address specific questions in the race/ethnicity subsets, and a reliance on self-reported adherence to hormone therapy.
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Last editorial review: December 13, 2018
Featured Image: General session during the Annual San Antonio Breast Cancer Symposium in San Antonio, TX. Courtesy: 2018 © MedMeetingImages/Todd Buchanan. Used with permission
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