Triple negative breast cancer is a relatively uncommon form of cancer. Here, we explain all you need to know about it.
Across the board, there is still lot we don't know about breast cancer. Triple negative breast cancer is not very common, and many people have not heard of it before. Here's everything you need to know about the basics.
What is triple negative breast cancer?
Triple negative breast cancer is a relatively uncommon form of breast cancer that is usually more aggressive and harder to treat than other types of breast cancer.
It’s known as triple negative because it lacks three molecules called receptors. All other types of breast cancer have at least one of three receptors: the oestrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2). These receptors are important for passing signals to cancer cells. For example, the hormone oestrogen stimulates the growth of some breast cancer cells through the oestrogen receptor.
Around 15% of all breast cancers – over 8,000 cases a year in the UK – are triple negative.
Why is triple negative breast cancer harder to treat?
Many of the most effective breast cancer treatments work by targeting receptors. For example, the drug trastuzumab kills breast cancer cells by latching onto the HER2 receptor, while tamoxifen works by blocking the oestrogen receptor and stopping oestrogen from stimulating breast cancer cells. Because triple negative cancers lack receptors, it’s not possible to treat them using targeted drugs like these.
Treatment for triple negative breast cancer is therefore limited to surgery, radiotherapy and chemotherapy. Because chemotherapy is not as targeted as drugs like trastuzumab and tamoxifen, it can cause significantly more side effects.
Are there any new drugs for triple negative in the pipeline?
The National Institute for Health and Care Excellence (NICE) – who decide which medicines will be available on the NHS in England – is currently considering a new treatment for triple negative breast cancer called atezolizumab. Also known as Tecentriq, this drug targets a receptor called PD-L1 which is found in triple negative breast cancer. Atezolizumab, in combination with the chemotherapy drug nab-paclitaxel, may be an option for women with previously untreated locally advanced or secondary triple negative breast cancer. A decision on whether to make atezolizumab available on the NHS is due in late 2019.
Later this year, NICE is also likely to consider another targeted treatment called pembrolizumab. Also known as Keytruda, pembrolizumab can be used before surgery in women with triple negative early breast cancer, and may also be an option for women with previously treated secondary triple negative breast cancer. Decisions on whether to make these new options available on the NHS are expected in 2020.
Is Breast Cancer Now funding research into triple negative breast cancer?
We have a dedicated Research Unit at King’s College London which is the only research unit in the UK focusing solely on understanding triple negative breast cancer and finding better ways to treat it.
Under the leadership of Professor Andrew Tutt, there are currently 29 researchers based at the unit, including Professor Ng and his team who study the role of immune cells in triple negative breast cancer. They are using imaging techniques to look at how immune cells enter the tumour environment and how this contributes to the growth and spread of triple negative breast cancer.
We also fund triple negative research elsewhere in the UK. For example, Professor Claire Lewis at the University of Sheffield is testing whether targeting two molecules called CXCR4 and VEGFA could prevent triple negative breast cancers from spreading around the body.
Dr Walid Khaled at the University of Cambridge is trying to understand how a protein called BCL11A, present in large amounts in triple negative breast cancer cells, is interacting with other proteins in these cells. He hopes that we may be able to kill triple negative breast cancer cells by using treatments to target these interactions.
Although this research may take some time to reach patients, it’s hoped these projects could lead to new treatment options for people with triple negative breast cancer.
Have there been any recent breakthroughs?
In 2018, a clinical trial part-funded by Breast Cancer Now found that for women with secondary triple negative breast cancer and a BRCA gene mutation, carboplatin outperformed standard chemotherapy, giving women extra time before their disease progressed.
Scientists at our Research Unit at King’s College London have also recently identified a target for new antibody-based treatments for triple negative breast cancer. Researchers have shown that triple negative breast cancer cells make high levels of a protein called the folate receptor alpha. They found that antibody-immunotherapies which targeted this protein significantly reduced the growth of triple negative tumours in mice. The team now hope to further develop and refine these novel approaches, with the aim of advancing them into clinical trials.
What causes triple negative breast cancer?
While we know many of the factors that affect your chance of developing breast cancer overall, we still don’t fully understand why some women develop triple negative rather than other types of breast cancer.
We do know that if you develop breast cancer at a young age, it’s more likely to be triple negative. Black women are also more likely to develop it.
If you carry a fault in the BRCA1 gene, you’re also more likely to develop triple negative breast cancer – in fact, most breast cancers caused by BRCA1 faults are triple negative. Because of this, if you don’t have a known history of breast cancer in your family but you’re diagnosed with triple negative breast cancer under the age of 50, you’ll be eligible for specialist genetic services to look for BRCA faults. You can read more about BRCA faults in our family history guide.
Are there any particular symptoms of triple negative I should look out for?
Although triple negative is different to other types of breast cancer in many ways, the signs and symptoms are the same. It’s important for all women to check their breasts regularly and discuss any unusual changes with their doctor.
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