Genetic testing: a numbers game

02 October 2020
Marie-Claire Platt

A study commissioned by Ovarian Cancer Action found 80% of people want access to genetic testing that could reveal an underlying lifetime risk of developing certain cancers. This Hereditary Cancer Awareness Week, OCA’s Head of Public Affairs and Research Marie-Claire Platt explores why offering everybody the choice to be tested (population testing) could give many the opportunity to catch cancer early or prevent it before it happens. 

Everyday I talk about numbers.

Carrying a BRCA gene mutation raises our risk of developing ovarian cancer up to 60%. Of breast cancer up to 85%. 1 in 400 of us carry a BRCA gene mutation and around 1 in 250 have Lynch syndrome (yet it’s thought 95% of people with Lynch syndrome are unaware that they have it). 

But here’s one that sticks: the current guidelines used by health professionals to help spot  those people who carry a BRCA mutation, and have a high risk of cancer, will only ever identify 50% of those men and women. 

To identify a woman as a carrier only after she develops cancer is a failure of cancer prevention

Dr Mary-Claire King, discoverer of the BRCA1 gene mutation

At the moment, the guidelines rely on a person’s family history of cancer to flag if it’s likely they’ve inherited a faulty gene. So if you have multiple cases of breast, ovarian or prostate cancer in your family, if you have been diagnosed with ovarian cancer, or a direct blood relative tests positive for a genetic variant following a cancer diagnosis, you are eligible for testing. 

This testing criteria based on personal and family history has already helped thousands of women discover their personal risk of cancer - knowledge they’ve used to help manage and lower that risk, keep on top of possible symptoms, and even personalise their cancer treatment.

But there are many more carriers out there who don’t have a family history of cancer - or are simply unable to trace it. Their risk of developing cancer is the same, but they have no warning, no opportunity to act before it hits. 

That’s unless we introduce population testing for BRCA gene mutations. By which we mean offering everyone the choice to have a simple blood test to reveal their genetic risk. This would give everyone in the UK the power to take their risk of cancer into their own hands.

So now we’re back to the numbers. 

We asked the public if they would want genetic testing to be available to all on the NHS and 80% said yes. 

And not only do people want it, but it saves the NHS money too. Recent research published by Professor Ranjit Manchanda showed that even if you test the entire population and reduce the risk in carriers, it’s cheaper for the NHS than paying for the alternative - the cancer treatment that so many will face unnecessarily.

If you take all these numbers it adds up to only one thing. Our vision of a future where no one develops hereditary cancer, or is diagnosed too late, is only possible when we introduce population testing. But we all know this is about so much more than numbers. It’s about Mum’s being there at their children’s weddings. Grandmas meeting their grandchildren for their first time. Sisters bickering into old age together. Population testing will save lives. 

So what are we waiting for?