SABCS 2022 | Race and clinical outcomes in the RxPONDER trial
Yara Abdou, MD, UNC School of Medicine, Chapel Hill, NC, discusses the race and clinical outcomes in the Phase III RxPONDER (NCT01272037) trial. A 21-gene recurrence score (RS) was established from the RxPONDER trial to guide treatment decisions among patients with early-stage breast cancer. Clinical outcomes with respect to race and ethnicity were analyzed from the trial to determine whether race is predictive of benefit in early breast cancer. The primary outcome was invasive disease-free survival (IDFS). The study included 4,048 participants with hormone receptor positive, HER2 negative (HR+/HER2-) breast, 1-3 involved axillary lymph nodes. There were no significant differences in tumor size, lymph-node involvement or the RS by race. However, there were more high-grade tumors amongst non-Hispanic (NH) Black patients compared to NH White and Asian patients. Overall five-year IDFS was lower for NH Black patients (87.0%) compared to that for Asians (93.9%), NH Whites (91.5%), and Hispanics (91.4%). Additionally, NH Black patients had a lower distant relapse-free survival compared to NH White patients and other races. Adjusting for RS, there was no statistically significant interaction between NH Black patients versus NH White patients and treatment arm for either premenopausal or postmenopausal women. However, due to the limited number of events in NH Black cohort, definitive conclusions on racial differences and treatment benefits could not be made. Overall, Black women with HR+/HER2- breast cancer, 1-3 involved lymph nodes and RS ≤ 25 had worse outcomes compared to White women despite similar RS results. This interview took place at the San Antonio Breast Cancer Symposium (SABCS) 2022 in San Antonio, TX.
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Transcript (edited for clarity)
The race and clinical outcome sub-analysis was focused on determining whether there were racial or ethnic disparities in the RxPONDER trial. Our study objectives were to evaluate the entire cohort by race for clinical pathologic characteristics, analyze the clinical outcomes by race, and determine whether race is predictive of treatment benefit in early hormone-positive breast cancer.
The study included about 4,048 women from the RxPONDER trial with known race and ethnicity...
The race and clinical outcome sub-analysis was focused on determining whether there were racial or ethnic disparities in the RxPONDER trial. Our study objectives were to evaluate the entire cohort by race for clinical pathologic characteristics, analyze the clinical outcomes by race, and determine whether race is predictive of treatment benefit in early hormone-positive breast cancer.
The study included about 4,048 women from the RxPONDER trial with known race and ethnicity. In regards to clinical characteristics, there were no significant differences in tumor size, or lymph node involvement, or even the 21-gene recurrence scores by race. However, there were more high-grade tumors amongst the non-Hispanic Blacks compared to non-Hispanic Whites and Asians.
In regards to outcomes, the non-Hispanic Black cohort had an inferior invasive disease-free survival of 87.2% compared to 91.5% in the non-Hispanic white cohort. On the other hand, the Asians had a superior invasive disease-free survival compared to the non-Hispanic Whites and other racial cohorts.
Additionally, the non-Hispanic Black patients had a lower distant relapsed-free survival compared to non-Hispanic Whites and other races. Adjusting for recurrence score, menopausal status, treatment arm, age, and grade did not seem to alter the impact of race suggesting that race was independently prognostic in that cohort. In terms of treatment effect, there was no significant interaction between race and treatment arm in either the postmenopausal or premenopausal groups. However, there was a limited number of events in the non-Hispanic Black cohort. Therefore, definitive conclusions about the racial differences in treatment benefits cannot be made.
We also looked at treatment compliance by race, and we found that non-Hispanic Blacks were more likely to accept a treatment assignment compared to non-Hispanic Whites and were just as likely to remain on endocrine therapy at that 6- and 12-month mark. This data suggests that the outcome differences are less likely attributable to lack of treatment compliance within that first year. However, data beyond the first year still immature, therefore longer follow-up is needed to confirm this finding.
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