Findings of a large, global clinical trial reported at the 2022 San Antonio Breast Cancer Symposium on December 6 and led by senior author Kevin Kalinsky, MD, MS, of Winship Cancer Institute of Emory University, found that non-Hispanic Black (Black) women with Hormone Receptor positive/HER2-negative breast cancer, with 1-3 involved lymph nodes and recurrence scores below 25, have worse outcomes than non-Hispanic white (white) women with similar diagnosis.
Black women had lower overall five-year invasive disease-free survival (IDFS) compared with the other racial and ethnic groups, and worse distant relapse-free survival (DRFS) than white women. DRFS is the length of time from the start of treatment for cancer that a patient is still alive and the cancer has not spread to other parts of the body.
HR+/HER2- is the most common subtype of breast cancer, accounting for some 68% of the estimated 287,850 new cases diagnosed each year. If diagnosed early, it is also one of the most survivable with a 100% five-year survival rate if the disease is detected and treated before it has metastasized and involves any other area of the body.
The phase 3 RxPONDER Trial (NCT01272037), conducted by the SWOG Cancer Research Network, a cancer clinical trials group funded by the National Cancer Institute, analyzed the clinical outcomes of 4,048 women with HR+/HER2- with respect to race and ethnicity. The women assessed included 2,833 white patients (70%), 248 Black patients (6.1%), 610 Hispanic patients (15.1%) and 324 Asian patients (8%). Black and white patients were the same ages.
Although there were no significant differences in tumor size, number of positive lymph nodes or the 21-gene recurrence scores across all racial/ethnic groups, Black and Hispanic women had significantly higher rates of grade 3 tumors than white and Asian women. Black women were more likely to accept and comply with treatment than white women, suggesting that their poorer outcomes are not the result of not complying with treatment.
|Kevin Kalinsky, MD, MS|
“These data demonstrate that there is a difference in outcome based on race/ethnicity in a large randomized trial,” says Kalinsky, who is the director of the Glenn Family Breast Center, Louisa and Rand Glenn Family Chair in Breast Cancer Research and director of breast medical oncology at Winship Cancer Institute of Emory University as well as associate professor in the Department of Hematology and Medical Oncology at Emory University School of Medicine. “Understanding why is critical, as is increasing the number of underrepresented minorities in clinical trials.”
Kalinsky, who collaborated on this study with first author Yara Abdou, MD, of the University of North Carolina, says that future studies will examine how tumor biology, gene groups, health care access and social factors, as well as treatment completion and adherence beyond the first year may contribute to outcome differences by race.
The RxPONDER Trial was funded by NIH/NCI grants U10CA180888, U10CA180819, U10CA180820, U10CA180821, U10CA180868, and U10CA180863; Susan G. Komen for the Cure Research Program; Hope Foundation for Cancer Research; Breast Cancer Research Foundation; and Genomic Health (now Exact Sciences Corporation).