Biological factors don't fully explain racial disparities for breast cancer type

December 7, 2017, UNC Lineberger Comprehensive Cancer Center

Higher risk of recurrence for black women with hormone receptor-positive, HER2-negative breast cancer compared with white women cannot be completely explained by underlying biological factors, University of North Carolina Lineberger Comprehensive Cancer Center researchers reported at the 2017 San Antonio Breast Cancer Symposium on Thursday, Dec. 7.

For with cancer, hormone-receptor positive, HER2-negative breast cancer is considered to be a type of breast cancer with a range of effective treatments, and a lower risk of compared to other cancer types, said UNC Lineberger's Katherine Reeder-Hayes, MD, MBA, MSc, who is an assistant professor in the UNC School of Medicine. Yet, historically, racial disparities have been greatest for women with this type of breast cancer than for other types, the researchers said. The biological features of patients' tumors partially explained this difference, but the researchers said it didn't explain it completely.

"We have different kinds of treatments for hormone-receptor positive, HER2-negative breast cancer; it's a lower risk of coming back, so you would think that's a 'good' kind of breast cancer to have," Reeder-Hayes said. "But that's actually the place where we see the biggest difference between black and in how things turn out. We are trying to understand why this is happening in order to improve outcomes for ."

In their study, the researchers reported findings of a disparity in between black and white women. While 8.6 percent of 1,371 of white women had a recurrence of hormone receptor positive, HER2-negative breast cancer, 14 percent of 1,403 black women had recurrence. For women with hormone receptor positive, HER2-negative cancer, they found gaps between black and white women's risk of recurrence even after taking into account the stage of the cancer and whether the women received chemotherapy. The study drew from data from the Carolina Breast Cancer Study Phase III, a prospective study of 2,998 women with breast cancer recruited from 2008 and 2013.

The researchers wanted to know if additional biological features not usually measured in the clinic could help explain the disparity. To try to answer this question, Melissa Troester, PhD, UNC Lineberger member and professor of epidemiology in the UNC Gillings School of Global Public Health, led an effort to categorize cancers for both black and white women by molecular subtype. Cancers were classified based on patterns of how genes are expressed within tumors using the PAM50 gene expression assay, of which Charles M. Perou, PhD, UNC Lineberger member, May Goldman Shaw Distinguished Professor of Molecular Oncology, and professor of genetics, and pathology & laboratory medicine, was an inventor.

In this previous study, which was published in the Journal of the National Cancer Institute, Troester and her colleagues found that while most women with the hormone-positive, HER2-negative clinical subtype had an intrinsic subtype called luminal A—a "better" prognosis breast cancer—some women had other intrinsic subtypes that are less common in hormone receptor-positive tumors, and that had a higher risk of returning after treatment. Black women had a lower frequency of luminal A breast cancer, and they had significantly higher relative frequency of the other non-luminal A breast cancer subtypes.

In their recent study, Reeder-Hayes, Troester and their colleagues found the difference in recurrence between black and white women was diminished after adjusting for clinical variables, and especially after accounting for molecular subtypes. However, the difference by race persisted even after considering these factors; black women still were 44 percent more likely to have recurrence. These results suggest that a combination of tumor biology and differences in access to care are influential for outcomes.

"Yes, there is biological heterogeneity in hormone positive, HER2-receptor negative disease, and yes, that seems to explain part of the gap in recurrence free-survival, but no, it doesn't explain all of it, which sends us down several other investigative paths to see what other factors contribute," Reeder-Hayes said.

Explore further: Aggressive breast cancers may contribute to racial survival disparities

Related Stories

Aggressive breast cancers may contribute to racial survival disparities

August 4, 2017
A higher proportion of aggressive breast cancer subtypes are seen in black women, University of North Carolina Lineberger Comprehensive Cancer Center researchers have found. The study findings help to explain a gap in mortality ...

Type 2 diabetes associated with risk of aggressive breast cancer in black women

November 15, 2017
African American women with type 2 diabetes (often referred to as adult-onset diabetes) are at a greater risk for developing breast cancer.

African-American women with type 2 diabetes may have higher risk for ER-neg breast cancer

November 15, 2017
Among African-American women, those with type 2 diabetes may have a higher risk of developing estrogen receptor (ER)-negative breast cancer.

Insurance plays significant role in breast cancer disparities

October 16, 2017
Differences in insurance account for a substantial proportion of the excess risk of death from breast cancer faced by black women, according to a new study. The study, appearing in Journal of Clinical Oncology, concludes ...

Pregnancy poses no greater risk to breast cancer survivors

October 26, 2017
A recent study published in the Journal of the National Cancer Institute indicates that pregnancy does not incur a greater risk of relapse for survivors of breast cancer. The safety of pregnancy for women with history of ...

Breast cancer recurrence defined by hormone receptor status

October 1, 2012
Human epidermal growth factor (HER2) positive breast cancers are often treated with the same therapy regardless of hormone receptor status. New research published in BioMed Central's open access journal Breast Cancer Research ...

Recommended for you

Metastatic lymph nodes can be the source of distant metastases in mouse models of cancer

March 22, 2018
A study by Massachusetts General Hospital (MGH) investigators finds that, in mouse models, cancer cells from metastatic lymph nodes can escape into the circulation by invading nodal blood vessels, leading to the development ...

Researchers examine role of fluid flow in ovarian cancer progression

March 22, 2018
New research from Virginia Tech is moving physicians closer to pinpointing a predictor of ovarian cancer, which could lead to earlier diagnosis of what is know as the "silent killer."

Could a pap test spot more than just cervical cancer?

March 22, 2018
Pap tests have helped drive down rates of cervical cancer, and a new study suggests they also could be used to detect other gynecologic cancers early.

Probing RNA epigenetics and chromatin structures to predict drug resistance in leukemia

March 22, 2018
Drug resistance is a major obstacle to effective treatment for patients with cancer and leukemia. Epigenetic modifying drugs have been proven effective for some patients with hematologic malignancies, such as myelodysplastic ...

Researchers identify compound to prevent breast cancer cells from activating in brain

March 22, 2018
Researchers at Houston Methodist used computer modeling to find an existing investigational drug compound for leukemia patients to treat triple negative breast cancer once it spreads to the brain.

Gene-based test for urine detects, monitors bladder cancer

March 22, 2018
Researchers at The Johns Hopkins Kimmel Cancer Center have developed a test for urine, gathered during a routine procedure, to detect DNA mutations identified with urothelial cancers.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.