Black women with early-stage hormone receptor-positive (HR+) breast cancer responded better to neoadjuvant endocrine therapy than their White counterparts, but those treated at a later stage did poorer, according to findings presented at the 2022 AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, held September 16-19, 2022. Because the results suggest different outcomes for hormone receptor-positive cancer in Black women, the researchers noted that precision medicine should be encouraged to treat this disease that behaves differently, not just across races, but also within races.
"Our findings suggest that neoadjuvant endocrine therapy alone may not be the best approach in Black women who present with more advanced tumors," said Veronica Jones, MD, Assistant Professor in the Department of Surgery, Division of Breast Surgery at City of Hope, who presented the study's results during the AACR conference. "More work is needed to understand the efficacy of endocrine therapy in providing durable response across races given the heterogeneity of hormone receptor breast cancer."
HR+ breast cancer is the most common subtype among all races, encompassing about 70 percent of all cases of breast cancer. Among all races, Black women suffer the highest mortality rate for HR+ breast cancer, dying at 4 times the rate as White women. Despite the disparity in outcomes, both races are treated the same way, largely with endocrine therapy targeting the hormone receptors.
"We need to understand if this is the right approach, especially in a population that suffers a much higher mortality rate," Jones said.
Study Details
To better understand the outcome disparities and rates of endocrine resistance between Black versus White women, Jones and colleagues analyzed 3,521 White women and 365 Black women with Stage I-III HR+ breast cancer from the National Cancer Database (NCDB). Their analysis evaluated change in tumor size, nodal status, and presence of metastases following neoadjuvant endocrine therapy which is treatment before surgery. Length of therapy was also considered.
At diagnosis, Black women were found to be 1.6 times more likely to have cancer detected in their lymph nodes, and 1.5 times more likely to have advanced Stage III disease compared to White women. Black women also were 1.5 times more likely to receive neoadjuvant endocrine therapy for longer than 24 weeks.
Overall, 0.8 percent of tumors were either down-staged to a local lesion or completely eliminated following neoadjuvant endocrine therapy. Black women with lower-staged disease I-II were 2.9 more likely to experience tumor down-sizing or elimination compared to White women. In contrast, 0.9 percent of tumors, all but two of which were diagnosed as Stage II or III, worsened to Stage IV. Black women were 2.6 times more likely to experience tumor upstaging than White women.
"We were able to identify that, while lower-stage cancers in Black women respond very well to endocrine therapy, higher-stage cancers in Black women do very poorly in response to endocrine therapy," Jones noted. "This suggests a different tumor biology that may impact the treatment we give."
Among the study's clinical implications, Jones said oncologists will need to do a better job distinguishing tumors based on their genetic profile to identify the best treatments. At the City of Hope, she noted that researchers are using RNA sequencing to look closer at genomic differences in hormone receptor breast cancer across races.
"In order to effectively treat hormone receptor breast cancer, we need to understand more about the tumor biology heterogeneity found within this subtype," Jones added. "To this end, our group would like to look closer at the patients included in the National Cancer Database (NCDB) to see why patients received certain treatments and how they responded. We would also like to investigate other ways of capturing endocrine therapy duration of treatment and adherence."
One limitation of the study is that percentages of estrogen and progesterone receptor positivity, which can correlate with response to endocrine therapy, were unavailable. The NCDB also did not contain information about how well patients adhered to endocrine therapy or how clinical tumor stage was determined, which may vary based on differential access to advanced imaging techniques.
Jones added there's also a need for increased numbers of clinical trials featuring a wider diversity of races and ethnic group participation to help determine best treatment options.
Warren Froelich is a contributing writer.