Using our DNA to tailor cancer treatment – how genomics is already changing the way we treat cancer

Approximately 38,000 people start chemotherapy treatment with a group of drugs call Fluoropyrimidines every year. What is already a trying and anxious time can be made worse by the fact that between 10 to 40 per cent of these people may have severe reactions to their treatment.

The reason some cancer patients experience severe side effects while others seemingly don’t can in part be explained by our DNA. Specifically, a gene that affects how our body breaks down chemotherapy drugs in our system.

This is why a service is being made available across England to allow cancer patients to be tested for this gene and reduce the chance of terrible side-effects and potentially even save their life.

Meet John

This is exactly what happened for John McGuire.

A builder all his life, he retired in 2012 to focus on spending time with his family and go on nice long walks with his springer spaniel, Barney, named after the barn he was born in back home in Ireland.

His retirement plans were interrupted though when he was diagnosed with a form of colorectal cancer and was referred to Guy’s Hospital in London to start treatment. But before his treatment even started, the cancer team took a sample of his blood and in his own words ‘he knew they were doing something special’.

Tailoring treatment to our DNA

The sample taken from John was used to see if there had been a change in a gene in his DNA called DPYD, which means his body may not be able to produce sufficient amounts of an enzyme that helps breakdown certain chemotherapy drugs, called Fluoropyridmines, and stops them building up to toxic levels.

If you have this change in this gene in your DNA and are given this particular form of chemotherapy it can lead to severe side-effects and in some rare cases, even death.

Once the cancer team identified the change in his DPYD gene, they knew that they needed to tailor the chemotherapy treatment to one that would be more effective and have less side-effects for John. They started reduced the dosage of the drug and monitored his progress.

John is halfway through his treatment and he is delighted with how the team at Guy’s Hospital have cared for him and how his treatment is progressing. He said, “I’ve have had little to no side-effects from my treatment and I think I am going to be very happy with the outcome.’

The Future

This test has been offered by some Trusts and services where local funding has been available, but now, this genomic test will be available across England and all cancer patients will have access to it no matter where they live.

The testing will be delivered by the seven Genomic Laboratory Hubs of the NHS Genomic Medicine Service (GMS) with results returned to each Trust and to the cancer team working with their patients.

This latest test is just one example of how the GMS is harnessing the potential of genomics to revolutionise how we approach diagnosing and treating cancer following the announcement of a new course of testing and treatment that target tumours based on changes in their DNA.

Since his diagnosis, John has been advised to stay inside and to self-isolate. Despite this he is in good spirits going into the New Year and this is in part due to how his treatment has been going and looks forward to being able to take Barney out again for nice long walks.

With tests like this, the ongoing research in genomic medicine and how it can inform cancer treatment, we hope more people can experience the same hope and belief as John.

Sue Hill

Professor Dame Sue Hill DBE FMedSci FRSB FRCP(Hon) FRCPath (Hon) FHCS (Hon) is the Chief Scientific Officer (CSO) for England and a respiratory scientist by background.

Throughout her career she has led on large-scale priority programmes across government and in NHS England including as the senior responsible officer for Genomics in the NHS, introducing a world-leading and nationwide Genomic Medicine Service, building on her work in heading up the NHS contribution to the 100,000 Genomes Project.

She has also played a pivotal role in the national COVID-19 programme leading the development and deployment of testing technologies into use for the UK population and co-directing the whole-genome sequencing of SARS-CoV-2 programme.