15 January 2020

Breast cancer breakthrough: Scientists discover over 350 DNA ‘errors’ that increase risk

A new study gives an optimistic forecast for better breast cancer outcomes and overall survival.

Breast cancer is the leading cancer affecting women in South Africa, according to CANSA. The National Cancer Registry indicates that one in 27 women is at risk of being diagnosed with the disease in their lifetime. 

But a new study casts a bright light on the fight to end this deadly disease. After looking at 200 000 people, scientists from the University of Cambridge identified 352 genetic mutations that increase an individual’s risk of developing the killer disease. The researchers, whose findings were published in Nature Genetics, believe that these mutations may impact as many as 190 genes.

According to the report, fewer than 40 genes had been previously recognised, making this breakthrough highly impressive.

Why this is good news

This new discovery paints a hopeful picture as it can help pinpoint which women are predisposed to developing breast cancer, and therefore allow them to be closely monitored. 

“This incredible haul of newly-discovered breast cancer genes provides us with many more genes to work on, most of which have not been studied before,” said Dr Alison Dunning from the University of Cambridge.

Dunning added that the large number of genes that are now known to play a role emphasise how complex the disease is, and that it will help researchers build a more detailed picture of how it arises and develops.

The human genome

The human genome contains between 20 000 and 25 000 genes, and while individuals actually share as much as 99.9% of the same hereditary material, 0.1% of our genetic variants make us unique. It's also what makes us susceptible to certain diseases.

What makes studying these genes even more intricate is that there are no single genes that cause diseases such as breast cancer, but rather a combination of these genes acting together to increase one’s risk of developing the disease.  

Science writer Ed Yong from the Atlantic writes: “These genes continue to be mysterious because they sit in parts of the genome that are hard to analyse with modern techniques. So when geneticists search for variants in the genome that are associated with diseases or physical traits, they often gloss over these duplicated genes entirely.”

However, Yong also points out that newer techniques are starting to solve these problems, with the recent discovery a case in point. 

Living with breast cancer

According to the World Health Organization (WHO), cancer affects more than two million women each year with an estimated 627 000 breast cancer-related deaths recorded in 2018. The WHO also notes that the rates are increasing in almost every region across the world.

Although breast cancer often manifests as a lump in the breast, not all lumps are cancerous, as explained in a previous Health24 article. Risk factors for the disease include, among others, age, age at first pregnancy, genetic inheritance, early onset of menstruation, and menopause after age 55.

Here are some of the most common symptoms of the disease, once a tumour has formed:

  • Unusual nipple discharge, sometimes stained with blood
  • Rash or crusting on the nipples
  • Lump or swelling in the lymph glands in the armpit
  • Sharp pain in the breast
  • Colour, shape and texture changes in the nipple
Breast lumps should never be ignored. If you notice a lump, it’s important to see your doctor right away.

Image credit: iStock

Ask the Expert

Cancer expert

CANSA’s purpose is to lead the fight against cancer in South Africa. Its mission is to be the preferred non-profit organisation that enables research, educates the public and provides support to all people affected by cancer. Questions are answered by CANSA’s Head of Health Professor Michael Herbst. For more information, visit

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