Tumor Biology More Important Than Race in Predicting Treatment Response in Breast Cancer

By Megan Brooks

December 16, 2021

NEW YORK (Reuters Health) - The biology of breast-cancer tumors appears to be a more important factor than race in predicting response to neoadjuvant therapy, according to new data from the I-SPY2 trial.

"The breast-cancer-mortality disparity between Black and white women is well established," lead author Beverly Kyalwazi of the University of Chicago Pritzker School of Medicine said in presenting the findings at the San Antonio Breast Cancer Symposium (SABCS).

Findings from the I-SPY2 trial suggest that race is "not significantly" associated with several key measures of breast-cancer-treatment outcomes, including pathologic complete response (pCR) and event-free survival, she said.

"This indicates that women with high-risk breast cancers are equally likely to experience a survival benefit from receiving targeted new adjuvant chemotherapy," Dr. Kyalwazi added.

The findings are based on 907 women with breast cancer (81% white; 12% Black; 7% Asian) followed for a median of 4.4 years.

As part of the I-SPY2 trial, the women had been randomly allocated to either standard neoadjuvant therapy with paclitaxel followed by doxorubicin and cyclophosphamide or paclitaxel plus an investigational agent (neratinib, veliparib and carboplatin, trebananib, ganitumab, MK2206, pertuzumab, TDM1 and pertuzumab, ganetespib, pexidartinib, or pembrolizumab).

Rates of pathologic complete response did not differ significantly by racial groups and there were also no significant differences in event-free survival or residual cancer burden, Dr. Kyalwazi reported.

This suggests that tumor biology is a more significant factor in breast-cancer survival than race, she told attendees.

In a subgroup analysis of women who did not achieve pathologic complete response, those with hormone-receptor-positive/HER2-negative breast cancer showed the greatest survival disparity between Black and white women, with Black women almost twice as likely to die during the study period than white women.

Weighing in on the findings, Dr. Theresa Shao, assistant professor of medicine, hematology and medical oncology at Icahn School of Medicine at Mount Sinai, in New York City, noted that "advances in breast-cancer treatment have dramatically reduced breast-cancer mortality, but African American women are still more likely to die from breast cancer than any other ethnic group."

"This study looking at neoadjuvant treatment in patients with breast cancer showed that biology rather than race is a more significant factor in predicting response to treatment. The fact that treatment outcome is more likely to be associated with tumor biology rather than race will allow us to focus more on strategies to ensure equal access to care among African American women," Dr. Shao told Reuters Health by email.

"More research looking at strategies to increase access to care will hopefully decrease mortality rate in African American women in the future," she added.

SOURCE: https://www.sabcs.org/ San Antonio Breast Cancer Symposium (SABCS), held December 7-10, 2021.