We discuss new and exciting research into personalised treatments for breast cancer patients.
Breast cancer is complex, over 20 different types of the disease exist, so we know that a one-size-fits-all approach to treatment simply doesn’t work. Treatments need to be personalised not just to the specific type of breast cancer, but to individual tumours in order to give patients the best chance of survival.
We hear all too often about the debilitating side effects that can come with breast cancer treatment and the impact that this has on day to day life. To make sure that patients only receive the treatments that will benefit them and reduce unnecessary over-treatment, we first need to understand the genetic faults that drive breast cancer and cause drug resistance and use this knowledge to predict how patients will respond to specific therapies.
Targeted treatments - thousands of lives saved, but we need to do better
Thanks to research, over the past few decades breast cancer patients have been given ever more targeted treatment according to their specific type of breast cancer, which is classified by ‘receptor status’ - such as oestrogen receptor positive (ER+). Post-menopausal women with ER+ breast cancer, for example, can be treated with drugs called aromatase inhibitors (AI), which are of great benefit to many patients: we now know that five years of AI treatment reduces the risk of post-menopausal women dying of their disease by 40 per cent within 10 years of starting treatment, compared with no hormonal treatment. Unfortunately this figure also tells us that AIs aren’t effective for everyone. We therefore need to find new ways to ‘sort’ patients into separate treatment groups by pinpointing the specific genetic mutations that influence how cancer cells respond to drugs.
The future is in our genes
When it comes to predicting which patients are at risk of their breast cancer returning or spreading, and which treatments are most likely to benefit them, we throw out the tea-leaves, put down the crystal ball and look at what their tumour can tell us.
Doctors need to be able to tell quickly and easily how patients will respond to treatments in order to select the drugs which will work best. Researchers at the Breast Cancer Now Toby Robins Research Centre have recently developed several exciting new ways of staying one step ahead of personalised medicine’s worst enemies: cancer returning and drug resistance.
Professor Mitch Dowsett has shown that a genetic test, known as Endopredict, can identify women at risk of secondary breast cancer more quickly and accurately than the test currently approved by NICE. Endopredict analyses a group of eight genes to classify patients according to their risk; patients with a low risk of their cancer spreading may be able to avoid chemotherapy and its harsh side effects, whereas those at a higher risk are likely to benefit from it.
Never far from the news headlines, Dr Nick Turner has developed a ‘liquid biopsy’, which can detect cancer DNA in the blood and identify patients who are not responding well to hormone therapies. Crucially, the test could allow drug resistance to be detected at an earlier stage, meaning that patients can be given alternative treatments more quickly, doubling the average time taken for their disease to progress. Find out more about Dr Nick Turner's work.
Genetic mutations – why catching them all is key
If personalised medicine is going to become a reality for breast cancer patients, we need to get a more complete picture of the genetic make-up of each tumour. Another recent study by Prof. Dowsett and Dr Pascal Gellert could bring us closer to accurately treating patients according to their unique genetic profiles.
Using samples from the POETIC clinical trial, the team analysed ER+ breast cancer tissue taken at diagnosis and during surgery and found that the genetic mutations present varied between samples in over a quarter of cases. This was an important and somewhat concerning finding, because many studies of personalised medicine rely on only one biopsy sample; Prof. Dowsett’s research suggests that these single biopsy studies may not be capturing all of the key genetic mutations that could be influencing how a patient will respond to treatment.
So how will these findings speed up our progress? Ultimately, this study highlights just how important it is to get a more detailed image of the genetic mutations found in each individual breast tumour. The more information we have, the more accurately we can ‘sort’ patients into different groups according to their genes and likely response to drugs, allowing these groups to be given the treatments they are most likely to benefit from.
Breast Cancer Now is very grateful to Walk the Walk, the Eranda Foundation, and The Trustees of The Mary-Jean Mitchell Green Foundation for their exceptionally generous support of Professor Mitch Dowsett’s research.