Breast cancer cell (photo: National Cancer Institute)
A new test could predict the risk of a woman’s breast cancer spreading within 10 years of diagnosis more accurately than the current NICE-approved test, Oncotype DX, scientists have found.
The new test, called EndoPredict, could also mean faster results for patients, potentially allowing decisions about treatment to be made more promptly.
The two tests have been developed to predict the likelihood of a woman’s breast cancer spreading to another part of her body — known as secondary (or metastatic) breast cancer — and therefore inform treatment decisions about whether chemotherapy should be offered in addition to standard anti-hormone treatments.
By identifying those at low risk of their disease spreading, women who would see little benefit from chemotherapy could be spared its gruelling side-effects.
The study was led by researchers at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust in collaboration with Queen Mary University of London, and published today in the Journal of the National Cancer Institute. It was funded by the charity Breast Cancer Now.
The research assessed the accuracy of EndoPredict in predicting whether breast cancer will spread in women with oestrogen receptor positive, HER2 negative (ER+/HER2-) disease and compared it directly for the first time with Oncotype DX, which the study’s authors originally played a crucial role in assessing.
Eight genes analysed
It is estimated that the ER+/HER2- subtype accounts for around two-thirds of all breast cancers, with more than 33,000 women being diagnosed with this form of breast cancer each year in the UK.
EndoPredict analyses the activity of eight different genes within a patient’s tumour sample. The test then uses this information, alongside the size of their tumour and their nodal status (whether their disease has spread to their lymph nodes) to give a score estimating their risk of their breast cancer spreading to other organs — where it becomes incurable — in the next 10 years.
This score, known as an ‘EPclin’ score, is then used to categorise patients into low- or high-risk groups, with anything lower than a 10% risk over 10 years being considered as ‘low risk’. Those at low risk could potentially be spared unnecessary chemotherapy treatment, while higher-risk patients would be recommended to go ahead with chemotherapy to lower their risk of developing secondary disease, for which there is currently no cure.
The researchers, led by Professor Mitch Dowsett and Dr Richard Buus from the ICR and The Royal Marsden, and Professor Jack Cuzick from Queen Mary University of London, analysed tumour samples from 928 patients diagnosed with ER+/HER2- primary breast cancer using EndoPredict.
These patients had originally taken part in the Arimidex, Tamoxifen Alone or in Combination (ATAC) clinical trial and were treated with five years of anastrozole or tamoxifen. Their Oncotype DX scores were already available for comparison and the researchers had an average of 10 years of follow-up data on the patient’s outcomes.
Low-risk patients identified
Both EndoPredict and Oncotype DX were used to identify patients with a ‘low’ or ‘high’ risk of their breast cancer spreading over 10 years.
The study found that EndoPredict identified women at ‘low risk’ of their breast cancer spreading more accurately than Oncotype DX. In the study, 5.8% of all patients identified as ‘low risk’ by EndoPredict went on to develop secondary disease compared with 10.1% of patients identified as ‘low risk’ by Oncotype DX.
Interestingly, the study also divided those patients whose disease hadn’t already spread to their lymph nodes into thirds (or tertiles) based on their risk scores.
Of the third of patients identified to have the lowest risk by EndoPredict, just one patient out of 227 (0.5%) went on to develop secondary breast cancer after 10 years, compared with 7% of the tertile identified to have the lowest risk by Oncotype DX.
By identifying such a large group of patients with an extremely good prognosis, in this way, EndoPredict could offer clinicians and patients reliable reassurance that chemotherapy can safely be avoided.
In addition, EndoPredict can be carried out locally at qualified molecular pathology labs, turning the results around within days and allowing the decision of whether chemotherapy should be given to be made promptly.
Awaiting NICE approval
Conversely, the Oncotype DX test is carried out at just one laboratory in the US and once the samples have been sent abroad for analysis, results can take up to 14 days to be returned.
Oncotype DX was approved by NICE in 2013 for use on the NHS in England and Wales as a cost-effective tool to determine a patient’s risk of breast cancer spreading. It was approved specifically for people with ER+/HER2- lymph node negative primary breast cancer who have been assessed (using non-genetic tests) as having an intermediate risk of their breast cancer spreading.
EndoPredict is yet to be formally assessed by NICE and is therefore only currently available privately in the UK. Any patients who think they could benefit from either of these tests should speak to their clinician.
While researchers welcomed the new data on EndoPredict, they also wanted to reassure patients that Oncoype DX continues to provide useful clinical information about recurrence of breast cancer.
Study lead author Dr Richard Buus, of the Breast Cancer Research Division at the ICR, said: “This study showed that a new test is more accurate than the current NHS standard test at detecting women at lowest risk of their breast cancer spreading to other parts of the body in the long term.
“It could help improve treatment for a large number of women with breast cancer by allowing doctors to better predict which women are least likely to go on to develop secondary cancer, and could therefore be spared from undergoing the chemotherapy often offered early on in treatment to reduce that risk.”
Baroness Delyth Morgan, Chief Executive at Breast Cancer Now, said: “This important study demonstrates the exciting potential of EndoPredict to identify breast cancer patients that will benefit little from chemotherapy. This test could give patients and their doctors invaluable reassurance that they may safely be spared chemotherapy’s gruelling side-effects.
“Oncotype DX remains a valuable tool for both clinicians and patients. But we need to see the best and most cost-effective technologies made routinely available on the NHS, and this research suggests EndoPredict could be another step forward.
“Based on this strong evidence, we would encourage NICE to consider this technology for routine use on the NHS.
“We need to continue finding ways to give patients the treatments most likely to work for them. Personalised medicine truly is the direction we need to keep moving in, both to give patients the best chance of survival and to avoid overtreatment.”
The samples tested form part of the ‘TransATAC’ collection of patient samples, the establishment of which was originally funded by Breast Cancer Now, with additional funding from AstraZeneca, and has received infrastructural support from the National Institute for Health Research Biomedical Research Centre at The Royal Marsden and the ICR.
Much of the research was conducted at the Breast Cancer Now Toby Robins Research Centre at the ICR, and also received funding from Cancer Research UK.