Science

Everything you need to know about the government plan for genetic testing to treat cancer patients

Millions of patients could have their DNA tested as genome sequencing becomes as routine as MRI or CT scans.

The British government’s chief medical adviser has unveiled plans where genome-based personalised medicine could open up for cancer patients within five years.

The “genomics dream” outlined by Professor Dame Sally Davies would see millions of patients having all their DNA tested as genome sequencing becomes as routine as MRI or CT scans.

Here is everything you need to know about the human genome and the proposed genetic testing to help treat cancer patients:

What is the human genome?

DNA sequence.
A human genome contains 3.2 billion letters of genetic code (Giotto/Getty Images)

A genome is the genetic material of an organism.

In humans, it is made up of 23 chromosome pairs. Every person’s genome contains 3.2 billion “letters” of genetic code, amounting to two terabytes of data.

Within the genome are 20,000 genes – stretches of DNA that provide the “software” for making proteins.

Other parts of the genome act as “dimmer switches” regulating the activity of genes.

How will it help cancer patients?

Genetic research.
The hope is that researchers will be able to compare a patient’s normal DNA with cancerous DNA and come up with personalised treatments (Pogonici/Getty Images)

Having access to this genetic blueprint can make a huge difference to the diagnosis and treatment of someone with cancer or a rare disease.

In the case of cancer, tumour cells develop a different genome to normal cells. Comparing a patient’s normal and cancerous DNA can provide valuable clues about the best form of treatment.

However, this information is not set in stone. Cancers evolve rapidly and alter their DNA, which can make them resistant to treatments.

Genome testing at regular intervals can help clinicians keep up in the arms race with cancer and guide ongoing therapy.

It can also help distinguish between aggressive and deadly cancers and slow-growing tumours that may never threaten a patient’s life.

Why is the government looking at genomics-based treatments?

Cancer patient with her doctor.
The hope is that genome testing could lead to speedier diagnosis and treatment (Megaflopp/Getty Images)

For adults and children with one of the 7,000 recognised rare diseases, genome testing could lead to far speedier and more effective treatment.

About 3.5 million individuals in the UK has a rare disease, many of them children under the age of five.

Currently having a rare disease identified involves multiple tests and several consultations.

The average patient sees five different doctors and is misdiagnosed three times before the nature of their illness is finally known. Reaching the end of this journey takes four years on average.

By reading a patient’s DNA rather than relying on the observation of often subtle symptoms, genomics testing can allow much faster diagnosis of rare diseases.

How will it work?

Professor Dame Sally Davies.
Professor Dame Sally Davies, the Government’s chief medical adviser (Yui Mok/PA)

Currently, genetic testing of NHS patients in England is conducted through 25 regional laboratories and a plethora of smaller ones operating along the lines of a “cottage industry”, according to Dame Sally.

Her chief recommendation is to centralise all the labs and establish a national network providing equal access to the tests across the country.

Within government, a new national genomics board would be set up, chaired by a minister, to oversee the expansion and development of genomic services taking into account new advances within the rapidly evolving technology.

Her report calls for a simplified two-stage consent system and make it easier for patients to get involved in research studies and clinical trials.

Speaking at a news briefing in London, Dame Sally said she hoped to see the new system fully operational within five years.

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