In TNBC, Pathologic Complete Response May Vary by Race/Ethnicity

Among patients with triple-negative breast cancer (TNBC) who received neoadjuvant chemotherapy, the odds of achieving pathologic complete response (pCR) and improved overall survival (OS) may vary by race/ethnicity, according to results from a retrospective cohort study.

Compared with white women, Black women with TNBC were less likely to achieve pCR (OR 0.89, 95% CI 0.83-0.95, P=0.001), while Hispanic women were more likely (OR 1.19, 95% CI 1.08-1.31, P=0.001), reported Maggie L. DiNome, MD, of Duke University School of Medicine in Durham, North Carolina, and colleagues.

Unadjusted OS was significantly higher for those with pCR compared with those with residual disease (5-year OS, 0.917 vs 0.667, log-rank P<0.001), but the effect of achieving pCR on OS did not differ by race/ethnicity (interaction P=0.10), they noted in the Journal of Clinical Oncology.

After adjusting for demographic, socioeconomic, tumor, and treatment variables, including achievement of pCR, Black race was not associated with worse OS compared white race (HR 1.04, 95% CI 0.98-1.1, P=0.23), but Hispanic (HR 0.76, 95% CI 0.69-0.85, P<0.001) and Asian (HR 0.64, 95% CI 0.55-0.75, P<0.001) race/ethnicity were associated with improved OS.

“Understanding the influences, including biologic factors that may contribute to these observed differences in outcomes, is paramount to improving treatment strategies and survival for patients with this otherwise aggressive breast cancer subtype,” DiNome and colleagues wrote.

DiNome told MedPage Today that TNBCs “may not all be the same.”

“Clearly there is something going on,” she said. “Certain races may have less responsiveness to our standard treatments, and further research needs to be done to find more effective therapies for these patients.”

In examining the question of whether a delay in treatment could explain the difference in outcomes, it turned out that both Black and Hispanic women started therapy an average 5 weeks later than white women, DiNome noted.

“This tells me there is some inherent biologic sensitivity or resistance where it doesn’t matter when you start treatment, you’re either going to get a response or no response,” she said. “We need to be looking into biologic differences that might be contributing to that difference in treatment response.”

“This was a hypothesis-generating study that was asking the question of whether there is a difference in response to treatment based on race, and I think our study shows there is,” DiNome added. “And that opens the door for the next steps — looking at what these differences are, and how we can address them.”

For this study, the authors used data on 40,890 patients with stage I-III TNBC in the National Cancer Database from 2010 to 2019. All had received neoadjuvant chemotherapy followed by surgery.

Median age was 53 years, 64% were white, 23.7% were Black, 8% were Hispanic, and 3.3% were Asian. Overall, 30.5% of white women, 27% of Black women, 32.6% of Hispanic women, and 28.8% of Asian women achieved pCR.

Age <50 years and annual income ≥$48,000 were associated with improved OS, whereas government insurance, grade 3 tumors, larger tumor size, and lymph node positivity were associated with worse OS.