A large study published in Nature Genetics has revealed 12 new breast cancer genes found in women of African ancestry, which could help to better predict the risk of disease and highlight the risk difference in women of European descent.
Involving the American Cancer Society’s Cancer Prevention Studies, CPS-II and CPS-3, the study looked at more than 40,000 women of African ancestry in the US, Africa and Barbados, including more than 18,000 living with breast cancer.
Breast cancer is currently the most common type of cancer in the US, responsible for over 240,000 diagnosed cases every year. It occurs when breast cells grow out of control.
According to the American Cancer Society, black women in the US have significantly higher rates of breast cancer before the age of 50, as well as a 42% higher breast cancer death rate in comparison to white women.
Funded partly by the American Cancer Society, results demonstrated estimates about the risk of breast cancer in women of African ancestry based on mutations in the predisposition genes, excluding the already-recognised breast cancer genes BRCA1 and BRCA2.
Researchers then went on to develop a breast cancer risk score for women of African ancestry, which was found to be more accurate than currently available tools.
The risk score revealed that six of the abnormal genes found were associated with an elevated risk for triple-negative breast cancer, the most aggressive form of the disease, while women carrying all six genes were 4.2 times more likely to be diagnosed with triple-negative breast cancer when compared to those with none or only one of the variants.
In a follow-up study, the prevalence of pathogenic mutations in three genes, BRCA2, CHEK2 and PALB2, was higher in black women.
“This study provides evidence to promote health equity in genetic counselling and testing to help determine the risk of developing breast cancer,” said Lauren Teras, scientific director and lead, breast cancer research, population science, American Cancer Society, and highlights the importance of the necessary efforts needed to reduce barriers for genetic testing for black women.