'This is the first study to use high-throughput genomic analysis of African women,' said study lead author, Dr Olufunmilayo Olopade, director of the Centre for Clinical Cancer Genetics at the University of Chicago in Illinois.
Women of African descent are more likely to develop and die from triple negative breast cancer than women of other heritages and are, on average, more than 10 years younger than American women of other ancestries when diagnosed.
'An urgent need exists to address widening global disparities in breast cancer mortality that disproportionately affect women of African ancestry,' write the authors in the Journal of Clinical Oncology.
The international study took place over more than 20 years as part of the Nigerian Breast Cancer Study based in Ibadan, southwest Nigeria. During this time, breast cancer incidences have steadily increased throughout the region.
Some 1136 women with breast cancer took part in the study along with 997 women of similar ages and heritage who did not have the condition. The researchers sequenced 25 genes associated with higher risks of breast cancer and identified the mutations occurring in each of those genes.
'Based on state-of-the-art genomic technologies, two things were clear,' said study co-author Dr Mary-Claire King at the University of Washington in Seattle. 'Risks to Nigerian women who carry mutations in breast cancer genes are higher than risks to women in the US with mutations in the same genes. And inherited breast cancer plays a bigger role in the total occurrence of breast cancer in Nigeria compared to the US.'
As a result of the research, the international team has developed a model to help predict women at high risk of breast cancer in Sub-Saharan African women. This can be used to offer surveillance and interventions for women with a predisposition to breast cancer and could substantially reduce deaths from the condition. This is particularly important because the study also showed that breast cancer is diagnosed much later than in the US – 86 percent of patients in the study were diagnosed with advanced stage three or four breast cancer.
'Lessons learned in Nigeria can be transferred back to low resource settings in the US and other countries,' added study co-author Professor Adeyinka Falusi at the University of Ibadan.