New research led by Breast Cancer Now funded-scientists highlights a novel way to identify women who would benefit from a longer course of treatment to help stop their breast cancer coming back.

Monday 22 June 2015      Research blog
Professor Mitch Dowsett
Professor Mitch Dowsett

The test is one which NICE already recommends the NHS use to help make decisions about who gets chemotherapy, so this new purpose could find its way into the clinic very soon. We take a look at what this test is and get behind the new research.

Preventing breast cancer recurrence

Women with oestrogen receptor (ER) positive breast cancer are often treated with endocrine therapy (tamoxifen or aromatase inhibitors) for five years following surgery to try and stop the cancer coming back later in life. But while taking endocrine therapy significantly reduces mortality, and the risk of recurrence, it’s not a guarantee. It has become apparent that some women may actually benefit from treatment beyond five years because they are at a greater risk of recurrence. Being able to identify who these women are would be an ideal way to make sure that every patient receives the best possible treatment.

The new research out this week may have found the solution. Using a genetic test, called Oncotype DX, the researchers were able to show that they could accurately identify ER positive breast cancer patients who were at a high risk of developing recurrence in the five to 10 year window following diagnosis and five year treatment with hormone therapy. They argue that these women may benefit from having their hormone therapy extended beyond five years to help prevent recurrence.

Finding new purpose

The Oncotype DX test is a 21-gene test used primarily to work out who will benefit from chemotherapy following surgery in order to prevent recurrence. Not all women will need chemotherapy, so this test can help spare patients unnecessary treatment. Previous research carried out by Professor Mitch Dowsett showed that Oncotype DX was the best available test for this. As a result, NICE now recommends this test as an option to help doctors decide who does, and doesn’t, need chemotherapy.

The research published this week reveals a new purpose for Oncotype DX as a test to identify women who may benefit from 10 years, instead of five, of hormone therapy to help reduce their risk of recurrence. This prediction of risk was made using only the analysis of the oestrogen receptor (ER) gene out of the 21 genes present in the test. Women with high ER levels had a relatively low risk of recurrence in the first five years, but this risk doubled in the next five years. This could be caused by changes in the behaviour of surviving cancer cells once the patient’s five year treatment ends – suggesting that extended treatment time would benefit these patients.

Changing clinical practice

The important thing here is that the high ER levels are detectable at the start of treatment, so women who may benefit from 10 years of treatment can be identified very early on. Professor Dowsett has a track record of making discoveries that directly impact on how breast cancer patients are treated. This study is another one to add to that list as these findings could significantly improve how patients are diagnosed and selected for treatment.

About the author

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Dr Matthew Lam is a Senior Research Communications Officer at Breast Cancer Now. He has a PhD in breast cancer research and becomes enraged in the presence of pseudoscience.