Researchers discover genetic ‘volume control’ for inherited breast cancers

Understanding the faulty genes in cancer is vital for beating the disease

Back in the 1990s, Cancer Research UK scientists played a fundamental role in the discovery of two major “cancer genes”, BRCA1 and BRCA2. Inheriting a fault in one of these genes greatly increases a woman’s risk of breast cancer, and they’re also linked to an increased risk of prostate and ovarian cancer.

Thankfully, inherited faults in BRCA1 and BRCA2 are rare – for example, they’re only linked to five in every hundred cases of breast cancer.

But even then, not everyone with a faulty BRCA gene develops cancer – and until now, it hasn’t been clear why.

Working together with researchers around the world, Cancer Research UK-funded scientists have discovered that other subtle genetic variations, elsewhere in a woman’s DNA, can affect how likely a woman with a faulty BRCA1 gene is to go on to develop the disease.

The story appeared on the BBC News website and is covered in detail on the NHS Choices Behind the Headlines blog. They explain:

“The news is based on a large international study which furthers our understanding of the genetics of breast cancer and helps explain why some women are at higher risk. It identified two new variants associated with an increased risk of breast cancer for women carrying the BRCA1 mutation, as well as three variants associated with a reduced risk.”

This doesn’t mean that the combination of carrying one of these gene variations alongside a BRCA1 fault means that a woman definitely will (or definitely won’t) develop breast cancer. It means that she will be more or less likely to develop breast cancer than we might expect.

One of the researchers, Cambridge-based Dr Antonis Antoniou, likened the finding to “a volume control [that can] turn up or down the risk of developing breast cancer from faults in the BRCA1 gene”.

These findings also open the door to testing women who carry BRCA1 faults, to see if they are carrying the more risky gene variations too. But, as the NHS Choices team concludes:

“The idea of fine tuning genetic tests to offer women a more personalised assessment of their risk is certainly appealing. However, before this can be done, we must first understand more about the genetics of breast cancer. It is too early to discuss the use of these findings in preventative treatment.”

The paper referred to in the NHS Choices article – and elsewhere – was published in the journal Nature Genetics. But there were two other related papers published at the same time, both of which also involved Cancer Research UK-funded researchers. One of these papers shows that the same gene region can increase ovarian cancer risk (in women who don’t carry BRCA1 faults), while the other reveals four genetic regions linked to ovarian cancer risk.

Taken together, these papers are an important step forward in our understanding of how the subtle variations in our genes contribute to cancer risk – and area in which Cancer Research UK has made great strides in recent years.

Although it’s too soon to talk about personalised genetic tests for cancer risk, we hope that the knowledge generated from studies like these will ultimately feed into the development of more effective tests and screening, enabling doctors to identify people at greatest risk of cancer, saving lives through prevention and early diagnosis.