A new blood test is 100 times better at spotting malignant cells in patients battling early-stage breast cancer than other methods, research suggests.
Cambridge University scientists developed the personalised tool, which searches blood samples for circulating ‘tumour DNA’.
The test has been described as a ‘game-changer’, after a trial of 33 patients showed it can detect changes in levels of the DNA.
Researchers hope it could allow doctors to gauge if a patient is responding to drugs, potentially letting them avoid unnecessary chemotherapy.
The team who created the test, called TARDIS, said it was 100 times more sensitive at picking up on these genetic mutations than similar approaches.
A new blood test picks up malignant cells in women with early-stage breast cancer (stock)
One in eight women in the UK and US will develop breast cancer at some point in their lives, statistics show.
Around 30 per cent of those treated with ‘neoadjuvant’ therapy achieve a ‘complete response’, the researchers said.
Neoadjuvant therapy is considered a ‘pre-treatment’, for example chemotherapy to shrink a tumour before it is surgically removed.
Complete response is defined as there being no evidence of malignant cells in a patient’s breast tissue or lymph nodes.
Of those who achieve a complete response, up to 95 per cent are still free of the disease 10 years later.
Among these patients, the added value of surgery is questionable, experts wrote in the journal Science Translational Medicine.
The researchers, led by Dr Muhammad Murtaza, therefore set out to create a test that looks for signs of ‘residual disease’.
This could then be used to guide future treatments.
TARDIS was designed to pick up on ‘circulating tumour DNA’ (ctDNA), which is shed from malignant cells before entering the bloodstream.
It carries ‘the same cancer-specific mutations as tumour cells’, which allows doctors to monitor how a patient is responding to treatment.
However, ctDNA is often present in much lower amounts than DNA shed by non-tumour cells, which makes the former difficult to detect.
Therefore, rather than tracking a single mutation in a patient, the experts created a test that looks for dozens of them.
They first tested the device in ‘commercially available reference samples’ of ctDNA, where they knew the number of mutations.
TARDIS was then ‘programmed’ to analyse the amount of genetic material that would be found in a tube of blood.
WHAT ARE THE SYMPTOMS OF BREAST CANCER?
Around 55,200 people are diagnosed with breast cancer in the UK each year. One in eight women develop the disease during their lifetime.
The illness can cause a number of symptoms, but the first noticeable symptom is usually a lump or area of thickened breast tissue.
Most breast lumps aren’t cancerous, but it’s always best to have them checked by your doctor.
According to NHS Choices you should also see your GP if you notice any of the following:
- A change in the size or shape of one or both breasts
- Discharge from either of your nipples, which may be streaked with blood
- A lump or swelling in either of your armpits
- Dimpling on the skin of your breasts
- A rash on or around your nipple
- A change in the appearance of your nipple, such as becoming sunken into your breast
Breast pain isn’t usually a symptom of breast cancer.
In the second part of the experiment, it was tested in 33 women with stage one-to-three breast cancer that had not spread.
To make TARDIS personalised, the researchers identified mutations in each of the patients’ tumour biopsies.
TARDIS then tracked these mutations in the patients’ blood samples, which were taken before and after they underwent treatment.
TARDIS correctly picked up on the patients having less ctDNA in their bloodstreams once their treatment was complete.
Among the participants who responded best to chemo, TARDIS detected a 96 per cent decrease in ctDNA.
Those with ‘residual disease’ had an average ctDNA reduction of 77 per cent.
This suggests TARDIS could be used to manage an individual’s risk of their cancer returning, the researchers claim.
This may also prevent doctors ‘over treating’ patients with ‘intensive’ therapies that carry side effects, the researchers wrote.
They stress, however, TARDIS must be tested in larger studies before it can be used in hospitals.
The researchers therefore need to ‘scale up’ the technology so it works on hundreds of patients.
Professor Carlos Caldas, director of the Breast Cancer Programme at the Cancer Research UK Cambridge Centre, said: ‘This could be a game-changer.
‘Instead of patients undergoing six to eight cycles of chemotherapy (15-21 weeks of treatment), after one or two cycles (3-6 weeks) we would use the TARDIS test to look for a significant drop in circulating tumour DNA.
‘If a drop was not detected, the treatment could be stopped or changed.’
Professor Justin Stebbing, NIHR Research professor of cancer medicine and medical oncology at Imperial College London, said: ‘This is high quality science where DNA from cancer can be detected in the blood.
‘What’s really interesting is they can detect this ctDNA during treatment for early-stage breast cancer when it is potentially curable, not just when it’s spread.
‘It’s important to note this is a blood test designed for women already diagnosed with early-stage breast cancer – not a blood test for everyone – and is used to help tailor the best treatment for these breast cancer patients.
‘In the clinic both over and under-treatment of patients with early stage cancer remains a challenge as we don’t always know how much therapy to give, or when to stop it.
He added: ‘These results suggest blood-based residual disease testing during treatment can further help individualise the choice and extent of treatment, so we don’t end up using more chemotherapy than we should.
‘We still need to do larger studies in more patients to be sure how well this will work, but the hope is blood tests for tumour DNA may one day be used instead of biopsies to monitor patients more quickly, reliably and with better results.’