Breakthrough research finds two new breast cancer genes in black women in South Africa – The Mail & Guardian

In a breakthrough study, researchers at the University of the Witswatersrand have discovered two breast cancer genes that occur in black South African women, paving the way for the development of novel treatments for the African demographic.
(AFP)

In a breakthrough study, researchers at the University of the Witswatersrand have discovered two breast cancer genes that occur in black South African women, paving the way for the development of novel treatments for the African demographic. 

The genome-wide association study (GWAS) of breast cancer was the first of its kind to be done on African women living on the continent, and led to the discovery of high-risk gene mutations in two from Soweto, from a sample size of 2 485 afflicted with breast cancer. 

“Despite how many studies have been done on breast cancer, this is the first time we found that these particular mutations in these genes are associated with breast cancer,” said Mahtaab Hayat, the lead author of the study.

“It sort of alludes to the fact that results from other populations, or non-African populations can’t be transferred, or can’t be said to do the same thing in African populations.”

Breast cancer was the most commonly diagnosed cancer among women, making up 23.2% of all female cancer cases — significantly higher than cervical cancer at 15.9% and colorectal cancer at 4.5%. Together, these top three cancers accounted for 43.5% of all cancers diagnosed in women, according to a 2008-2019 report by Statistics South Africa.

The Stats SA report also shows that in 2019 breast cancer incidence was the highest among white women at 92.02 per 100 000 females, followed by Indian/Asian females at 53.39 and coloured females at 50.01. Black African females had the lowest breast cancer incidence rate at 21.56 per 100 000 females. 

“These differences highlight substantial ethnic variation in breast cancer incidence within the country. Despite having the lowest breast cancer incidence, blacks and coloureds had the highest mortality to incidence ratio as compared with Indian/Asians and whites, which suggests a worst survival rate for black and colored population,” said Jean-Tristan 

Brandenburg, the co-author of the study.

Breast cancer GWAS studies have been in existence for nearly 20 years, and findings have been widely published, enabling researchers to understand the cancer genetics and to develop tools and treatments to manage the disease, but the African population has been largely excluded from these studies, Brandenburg said. 

“Most studies involving individuals of African ancestry have focused on African American

cohorts — populations whose history, environment, and genetic background differ

significantly from those living in sub-Saharan Africa, where environmental, lifestyle and

genetic diversity is higher.” 

Inadequate funding for cancer research in South Africa delayed scientists from discovering the difference in the genome variants between African and non-African populations, Hayat said.

“Scientists who are doing these GWAS studies didn’t realise that the genomes are so different and that they wouldn’t be able to apply non-African results to African results in sub-Saharan African universities [because] they don’t have funding to be able to do this — they don’t have the capacity to be able to do these sorts of studies, either,” she said.

“One of the hurdles we also have to cross is being able to secure funding and also have the appropriate scientists who have experience in this sort of field to be able to do the studies.”

The African continent needs to invest in more capacity building to train future scientists, so that it does not lag behind, she added. 

The current breast cancer treatments in South Africa include a combination of surgery, breast reconstruction, chemotherapy and radiotherapy, and among the black population, mastectomy is often the primary treatment option, said Brandenburg.

He added that research shows there are still significant disparities in breast cancer screening, which lead to delayed diagnosis among black patients, although targeted therapies may become possible if newly identified genes are shown to have a significant effect on the cancer.

“While our current findings primarily identify genetic variants with small effects, they still contribute meaningfully to the overall understanding of breast cancer genetics,” Brandenburg said.

The researchers said they would expand their sample size to include African women from other countries to better understand the genetic architecture of breast cancer across the diverse ancestries and environmental contexts in Africa. 

“Ultimately, such expansion is crucial for promoting equity in breast cancer research, improving risk prediction models, and enabling the development of personalised treatment strategies tailored to African populations,” Brandenburg said.