In a new study entitled “Genetic variants in one-carbon metabolism genes and breast cancer risk in European American (EA) and African American (AA) women” researchers identified differences in genetic variants associated with breast cancer risk between European American and African-American women. Notably, these changes are modulated with dietary folate intake and may be a cause for increased incidence of aggressive breast cancer in African-American women. The study was published in the International Journal of Cancer.
Breast cancer is the most common cancer in women, responsible for an estimated annual death toll of 40,290 women in 2015, according to the American Cancer Society. Notably, while breast cancer incidence is higher in European American women, African-American women are more prone to develop and die from aggressive types of breast cancer, namely estrogen receptor (ER)-negative tumors. However, while this fact has been established for quite some time, the underlying cause for this racial difference remains largely unknown.
Past epidemiological studies suggested that decreased dietary intake of folate increases breast cancer risk. Folate is a key factor of one-carbon metabolic pathways that are important for DNA synthesis, establishing a role between genetics and dietary intake. Accordingly, genetic variants were already found in the folate-mediated one-carbon metabolism pathway and linked to breast cancer risk; however, these were never assessed in African-American women. Moreover, previous research focused only on a small number of genes and functional polymorphism (i.e., those that have been proven to influence gene functions).
In this study, a team of researchers at the Roswell Park Cancer Institute (RPIC) and collaborators at the Rutgers Cancer Institute of New Jersey and the Icahn School of Medicine at Mount Sinai School of Medicine, performed a large-case control study focusing on genetic variants of multiple genes (11 genes were studied) of the one-carbon metabolism pathway and determined their association with breast cancer risk in both European American and African-American women.
The authors studied a total of 1,275 European-American and 1,299 African-American women who were enrolled in the Women’s Circle of Health Study. The team found significant differences in genetic variations (Single Nucleotide Polymorphisms) between European-American and African-American women that were associated with overall increased risk for breast cancer in both study groups (polygenetic risk-score only and not single-SNPs). Notably, the team highlights that these differences may be modulated by dietary folate intake.
Dr. Gong, Assistant Professor of Oncology and Assistant Member of the Department of Cancer Prevention and Control at RPCI, noted in a press release, “These findings are provocative because they provide new evidence that, by disrupting key processes and ultimately contributing to gene instability, certain genetic variants and interactions in these key metabolic pathways may contribute to risk of breast cancer in both African-American and European-American women.”