Breast cancer relapse test can predict treatment benefits, study suggests

Using a test that measures gene activity could help to tailor treatment for some women with early stage breast cancer, new research suggests.

The test, called EndoPredict (EPCyclin), successfully predicted whether chemotherapy would be beneficial for patients with the most common type of breast cancer.

Professor Daniel Rea, Cancer Research UK’s breast cancer expert, said the test provides important information on whether a patient’s cancer is likely to be sensitive to chemotherapy. 

“The EndoPredict test has the potential to help some women diagnosed with early hormone receptor positive, HER2 negative breast cancer avoid needless chemotherapy, and may reassure those where it’s needed.”

He added that the research highlights the progress being made in genetic testing and could be a valuable addition to the tests available to doctors, helping them advise patients.

The results were published in the journal Breast Cancer Research and Treatment.

What is EndoPredict? 

EndoPredict is a test designed to predict the risk of breast cancer coming back. It looks for a genetic ‘signature’ in a sample of the tumour and gives a score between 1.1 and 6.2, which can help doctors assess how likely the cancer is to spread to a different part of the body in the 10 years following diagnosis. 

It’s one of several branded tests developed for this purpose and was recommended for use in England and Wales by the National Institute of Health and Care Excellence (NICE) in December 2018.

But unlike new cancer drugs, tests like these don’t automatically get funded when NICE recommends them and it’s up to local NHS leaders to make them available.

Research has shown that EndoPredict and other tests, including the PAM-based Prosigna test and Oncotype Dx, vary in accuracy when predicting the long-term risk of someone’s cancer coming back.

“Trials in the UK are ongoing to provide more evidence to help us make the best use of these tests,” said Rea.

This includes a clinical trial testing the benefits of using Prosigna in over 4,500 women with breast cancer.

Predicting treatment success

The Cancer Research UK-funded research analysed results from 3 clinical trials involving over 3,700 women whose breast cancer was fuelled by the hormone oestrogen, but did not test positive for a molecule called HER.

Scientists looked back at the results to see if the EndoPredict test results could help to predict how patients would respond to treatments.

Patients deemed at high risk of their cancer spreading benefitted from the combination of chemotherapy and hormone therapy. Women who had the combination were less likely to see their cancer spread to other parts of the body than those taking hormone therapy alone.

But these benefits were not as obvious for women deemed at low risk of their cancer spreading, suggesting they could opt out of chemotherapy treatment and avoid the associated side effects.

The study focused on if the cancer had spread to other parts of the body (metastasis), it did not look at survival benefits. 

Lead author Dr Ivana Sestak, from the Wolfson Institute of Preventive Medicine, said the results can inform specific treatment recommendations for women.

“Our data shows that using the EndoPredict test to assess the risk of metastasis can spare women unnecessary chemotherapy,” she said.

EndoPredict isn’t the only test that could spare some women chemotherapy. In 2018, the Oncotype Dx test was also shown to help tailor treatment for some women with early stage breast cancer.