Improving cancer gene tests to guide better treatment for ER-positive breast cancers

Some oestrogen receptor (ER) positive breast cancers can come back after treatment. Sometimes many years later, when people least expect it. As long as that’s the case, people are left living in fear that their breast cancer could return. Not knowing what the future holds.

In other types of breast cancer, doctors often use the information from cancer gene tests to tailor treatment plans. This can help make sure people get the treatment they need, and others are spared gruelling side effects.

But ER-positive breast cancer cells that have spread to the lymph nodes behave differently from those in the breast. And right now, cancer gene tests aren’t used to tailor treatments for people with this type. That means some people could be enduring the harsh side effects of treatments they can safely avoid. Or for others, it could mean their risk of relapse isn’t properly understood.

That’s not good enough. So we’re researching now.

So that everyone can receive the treatment most effective for their tumour.

When breast cancer is diagnosed, sometimes cancer cells are also found in the neighbouring lymph nodes. Unless treated successfully, the disease can spread even further – from the lymph nodes to other parts of the body. We know that these breast cancer cells act differently. But cancer gene tests, which are used to predict how likely the ER-positive disease is to come back or spread, focus only on the tumour in the breast.

Arran and his team think we could select treatments better if cancer gene tests were used on breast cancer cells in the lymph nodes as well. And their earlier research has already shown this could change whether chemotherapy is recommended in around 30% of cases.

Now, Arran and his team are comparing test results between the tumour and the affected lymph nodes. They’re using one cancer gene test and samples from 282 people with early ER-positive breast cancer. If the results differ between the tumour and the lymph nodes, the researchers will work to understand why.

The team also want to understand why some ER-positive breast cancers resist treatment and spread. So they’re studying samples from 162 people with ER-positive breast cancer that came back during or after treatment. They want to understand the differences in proteins, DNA and gene activity. And doing so will help them understand if treatment decisions using cancer cells present in the lymph nodes could help to avoid treatment resistance and spread.

If people receive treatments that aren’t the most effective for their tumour, breast cancer can come back. But we also know that some people can safely avoid additional treatment and the gruelling side effects from drugs that they don’t need.

Getting this right is key. And that’s what this project is about. It could help pave the way to more personalised and effective treatments for ER-positive breast cancer. And it could give us insights to stop tumours resisting treatment.

Each year in the UK, around 44,000 people will be diagnosed with oestrogen receptor (ER) positive breast cancer.