Breast cancer gene test could spare some women chemo

A test that measures gene activity can help tailor treatment for some women with early stage breast cancer, according to a clinical trial.

Scientists used the Oncotype Dx test to predict how likely hormone receptor positive breast cancer was to come back after surgery. Hormone therapy alone was as good as a combination of chemotherapy and hormone therapy in women with an intermediate risk of their cancer returning.

This would mean those women can be spared chemotherapy, and its associated side effects, after surgery.

Scientists previously found that women with a low risk of their cancer returning can receive hormone therapy alone. And experts said the latest trial results should quickly change clinical care for those at intermediate risk too.

Professor Arnie Purushotham, senior clinical advisor at Cancer Research UK, said that by grouping patients based on how likely their cancer is to return, the trial shows great potential to ensure treatment is kinder without compromising its effectiveness.

The results from the phase 3 TAILORx study were presented at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, and are published in The New England Journal of Medicine.

What is Oncotype Dx?

Oncotype Dx 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 0 and 100, which can help to direct treatment decisions.

It’s one of a few branded tests that have been developed for this purpose and is recommended for use in the UK by the National Institute for Health and Care Excellent (NICE). But this decision is being reviewed.

Research has shown that Oncotype Dx and other tests, including Breast Cancer Index and EndoPredict, vary in accuracy, particularly when predicting the long-term risk of someone’s cancer coming back.

What did the study show?

Previous research has shown that women with a low Oncotype Dx recurrence score (less than 10) are likely to respond to hormone therapy alone, whereas those with a score above 26 benefit from having a combination of chemotherapy and hormone therapy.

But the best treatment for those with a score in the middle has been unclear.

For the TAILORx study, scientists recruited over 10,000 women with the most common type of breast cancer, called oestrogen-receptor positive (ER+) HER2-negative breast cancer. The patient’s cancer could not have spread to the lymph nodes.

Six in 10 women had a recurrence score of between 11 and 25, and were randomly assigned to have either hormone therapy or a combination or hormone therapy and chemotherapy.

Scientists found that giving hormone therapy alone was as good as the combination of chemotherapy and hormone therapy in women with the intermediate score. Survival was similar in both groups, with over 9 in 10 women still alive 9 years after treatment.

A more personalised approach to treatment

With the results of this trial doctors now have a clearer answer for how to tailor treatment for most women with the most common type of early stage breast cancer.

“Our study shows that chemotherapy may be avoided in about 70 percent of these women when its use is guided by the test, thus limiting chemotherapy to the 30 percent who we can predict will benefit from it,” said lead researcher Dr Joseph A. Sparano, associate director for clinical research at the Albert Einstein Cancer Center and Montefiore Health System in New York.

The latest results should mean more women can avoid chemotherapy, and its associated side effects, without compromising the effectiveness of their treatment.

“These data provide critical reassurance to doctors and patients that they can use genomic information to make better treatment decisions in women with early-stage breast cancer. Practically speaking, this means that thousands of women will be able to avoid chemotherapy, with all of its side effects, while still achieving excellent long-term outcomes,” said ASCO expert Dr Harold Burstein.

But in a discussion of the results, Dr Lisa Carey, from the University of North Carolina in the US, drew attention to some of the subtle differences between the groups. Women aged 50 or younger with a recurrence score of 16-25 did seem to gain some benefit from adding chemotherapy to hormone therapy. 

Carey pointed to some “grey areas” at the boundaries of the recurrance scores that need futher investigation, and said patients would need to discuss these details with their doctors before any decisions on treatement are made. “Nothing magical happens” at the point where a low score becomes intermediate or intermediate becomes high risk, she cautioned.

Where did these results come from?

The ASCO annual meeting is the largest gathering of clinical cancer experts in the world.

Researchers share preliminary and more advanced results. These come from small, early stage studies through to large randomised clinical trials.

In some cases, the results will go on to change how patients are treated. But most of the results are yet to be published in a scientific journal, so only offer an early glimpse of what these trials may later confirm.