Whitney Palmer

Aggressive Breast Cancer in African-American Women: Investigating the Genetic Link

Published in the 2009 University of North Carolina at Chapel Hill School of Nursing Research Chronicle

African-American women experience less breast cancer than women of other ethnicities. However, the breast cancers these women develop are often more invasive and aggressive. Assistant professor Theresa Swift-Scanlan is investigating the reasons behind this disparity and believes the answer lies in understanding epigenetic modifications to women’s DNA and how they are affected by lifestyle behaviors and environmental exposures. Epigenetic modifications are molecular level changes that alter gene expression without altering the primary sequence of DNA.

According to Swift-Scanlan, African-American pre-menopausal women are more likely than women of other ethnicities to develop basal-like breast cancer, a tumor subtype that does not have receptors for estrogen or the growth factor Her2. Basal-like tumors are resistant to effective therapies that target these receptors, such as tamoxifen and herceptin. The end result is that these tumors are very difficult to treat and are associated with increased morbidity and mortality.

According to previous data, Swift-Scanlan said, basal-like tumors occur in white women and other ethnic groups at all ages, just at a lower frequency than in African-American pre-menopausal women. Differences in the frequency of this tumor subtype appear to be due to varying distributions of risk factors

Asst. Prof. Theresa Swift-Scanlan conducting research into the epigenetics of breast cancer in her research lab.

across ethnic groups. Risk factors for basal-like tumors include not breastfeeding and larger waist-to-hip ratios. Unlike other breast cancer subtypes, having more children at a younger age appears to increase rather than decrease risk for basal-like breast cancer.

The Susan G. Komen Foundation awarded Swift-Scanlan a three-year, $450,000 Career Catalyst in Cancer Disparities Award to study gene methylation in basal-like breast cancer and four other tumor subtypes. The grant funds her efforts to determine whether DNA methylation – which can silence genes by changing the way the DNA is packaged within the cell – in concert with facts known about breast cancer subtype risk factors, could unearth ways to reduce mortality from the disease among African-American women. She also has funding through a National Institutes of Health Career Development Award.

Swift-Scanlan also hopes to identify genes that, when methylated, could contribute to early disease detection and risk assessment for all women.

“I hope that this research will help women in the decision making process,” she said. “Deciding what to do after a breast cancer diagnosis is a very personal and profound choice. Having this knowledge could help providers assist women in making the best decision for them while avoiding the problem of over- or under-treating the disease.”

Swift-Scanlan will analyze breast tissue samples and clinical data from at least 160 African-American women enrolled in the Carolina Breast Cancer Study, 80 of whom are pre-menopausal and 80 who are post-menopausal. Her main collaborators are genetics associate professor Charles Perou at the Lineberger Comprehensive Cancer Center and epidemiology professor Robert Millikan at the School of Public Health.

March 23, 2010 - Posted by wjpalmer | Family, Healthcare | breast cancer research, breast cancer tumor research, epigenetics of breast cancer, helping women select best breast cancer treatment