Yara Abdou, MD, on Race and Clinical Outcomes in the RxPONDER Breast Cancer Trial
2022 San Antonio Breast Cancer Symposium
Yara Abdou, MD, of the University of North Carolina, discusses results from the RxPONDER SWOG S1007 study, which showed that non-Hispanic Black women with hormone receptor–positive/HER2-negative breast cancer with one to three involved lymph nodes and a recurrence score of ≤ 25 have worse outcomes than non-Hispanic White women. In addition, Black patients were more likely to accept treatment assignment than their White counterparts and were just as likely to remain on estrogen therapy at 6 and 12 months, suggesting that outcome differences may be less likely attributable to lack of treatment compliance within the first year (Abstract GS1-01 ).
Disclaimer: This video transcript has not been proofread or edited and may contain errors.
Racial disparities in breast cancer outcomes continue to be a major healthcare challenge. US Black women have similar incidents, yet 40% higher breast cancer mortality, compared to white women. Therefore, more studies are needed to improve outcomes for minority women with breast cancer. Our study, in particular, focused on determining whether there were racial disparities in the RxPONDER trial. The RxPONDER trial is what established the clinical utility of the 21 gene recurrence score in hormone positive lymph node positive breast cancer. Our study objectives included looking at clinical pathological characteristics by race, analyzing clinical outcomes by race, and determining whether race had any effect on treatment benefit. This study included about 4,048 women with hormone positive lymph node positive breast cancer and known race and ethnicity. When looking at clinical characteristics, we did not find any significant differences in number of positive lymph nodes or tumor size across all racial cohorts.
Additionally, the recurrence score distribution also was pretty similar across all racial cohorts. However, the histologic grade was significantly different where non-Hispanic Black patients were noted to have fewer low grade tumors and more high grade tumors, compared to non-Hispanic whites. In regards to outcomes, non-Hispanic Black patients had inferior invasive disease-free survival and inferior distant relapse-free survival, compared to non-Hispanic whites. On the other hand, Asians had superior outcomes, compared to non-Hispanic whites and other racial cohorts. In a multi-variable model, when we adjusted for recurrence score, treatment arm, age, and grade, it did not alter the impact of race, and we continued to note worse outcomes for non-Hispanic Blacks, suggesting that race is independently prognostic. In terms of treatment effect, there was no significant interaction between race and treatment arm. However, there were a limited number of events in the non-Hispanic Black cohort.
Therefore, definitive conclusions on whether race has any effect on treatment benefits cannot be made at this time. Our studies, similar to prior studies, indicate racial disparities in breast cancer, particularly in the hormone positive group. Therefore, more studies are needed to improve outcomes for these patients. Next steps of our research will include looking at possible causes of these noted disparities, so we will be looking at a tumor biology differences by race, particularly gene groups, across all racial cohorts. We will also be looking at non-biological factors, including social determinants of health, because being on a clinical trial doesn't guarantee equal access to care. And treatment can still defer within a clinical trial.
Joseph A. Sparano, MD, of the Tisch Cancer Center at Mount Sinai Health System, discusses long-term clinical outcomes data that continue to show many women with early breast cancer can safely forgo chemotherapy, when guided by the 21-gene recurrence score result. The longer follow-up also showed that recurrences of breast cancer continue to occur years after the original diagnosis, although these recurrences were not prevented by chemotherapy use. Racial disparities were not explained by inequities in social determinants of health or treatment adherence, with Black women at higher risk of early recurrence within the first 5 years of diagnosis, but not later recurrence after 5 years (Abstract GS1-05).
Marleen Kok, MD, PhD, of the Netherlands Cancer Institute, discusses the most important advances in early breast cancer treatment during the past year for patients with triple-negative, HER2-positive, and estrogen receptor–positive disease. Dr. Kok also addresses long-term treatment toxicities and quality of life.
Mariana Chavez-MacGregor, MD, MSc, of The University of Texas MD Anderson Cancer Center, discusses phase III results from the SWOG S1207 trial which was designed to evaluate the role of adjuvant everolimus in combination with adjuvant endocrine therapy among patients with high-risk, hormone receptor–positive, HER2-negative early-stage breast cancer. Adding everolimus did not improve invasive disease–free or overall survival and was associated with high rates of adverse events (Abstract GS1-07).
Mafalda Oliveira, MD, PhD, of Spain’s Vall d’Hebron University Hospital and Institute of Oncology, discusses findings from the SERENA-2 trial, which compared the next-generation selective estrogen receptor degrader camizestrant to fulvestrant in patients with hormone receptor–positive, HER2-negative breast cancer. Camizestrant, which can be taken as a daily pill (as opposed to fulvestrant, which must be given via injection), improved progression-free survival by up to 42% (Abstract GS3-02).
Per Karlsson, MD, PhD, of Sweden’s University of Gothenburg and the Sahlgrenska Comprehensive Cancer Center, discusses results from the POLAR study, which was a meta-analysis of three clinical trials of breast-conserving surgery with or without radiotherapy. POLAR is the first genomic classifier that appears not only to be prognostic for locoregional recurrence, but also predictive of radiotherapy benefit. Although patients with breast cancer who had a high POLAR score benefited from radiotherapy, patients with a low score did not, and may be candidates for omission of radiotherapy after breast-conserving surgery (Abstract GS4-03).