Hormone Sensitive Breast Cancer

Hormone sensitive cancers have large numbers of hormone receptors and are often referred to as ‘hormone-receptor positive’. This means that female hormones fuel their growth. Around 75% of breast cancers are hormone-sensitive.

Tamoxifen and aromatase inhibitors are highly effective treatments for hormone sensitive breast cancer and have helped save thousands of lives. However, not all hormone sensitive breast cancers respond to treatment in the same way. For this reason, every patient needs a tailor-made treatment programme.

Breakthrough’s Professor Mitch Dowsett is leading an investigation into ways to identify which women will respond most effectively to tamoxifen and which to the alternative anastrozole. This will help us develop treatments specific to each patient’s tumour type and ensure women are treated most effectively. .

Some women can become resistant to anti-hormone therapy. To counter this, Professor Alan Ashworth is using a new technology called RNA Interference to study resistant cancer cells. He is looking for chemicals that will re-sensitise cells to tamoxifen, for development into potential new treatments.

Another Breakthrough study has shown for the first time that a single drug can simultaneously attack hormone sensitive cancer cells in two different ways. This discovery could lead to further two-in-one treatments – potentially reducing the number of drugs women with hormone-positive breast cancer will need to take in the future.

The ‘Molecular Endocrinology’ team led by Dr Lesley-Ann Martin are finding ways to overcome drug resistance in hormone-sensitive breast cancers. They are taking a variety of approaches to do this. For example, they are investigating whether molecules known as ‘signal transduction inhibitors’ could be given in combination with hormone therapies to prevent tumours becoming resistant to treatment.

They are also using a method called ‘array CGH’ to analyse the genetic make-up of breast tumours. They will investigate whether specific sections of DNA are duplicated or deleted in breast tumours that are resistant to treatment.

Scientists in Edinburgh are using powerful molecular pathology technology to study hormone sensitive breast cancer cells that are resistant to tamoxifen with those that are not. They aim to discover how resistance develops and to find ways to overcome this. 

Göran Landberg and his team in Manchester use a method called ‘microarrays’ to analyse the genetic make-up of breast tumours which  should allow scientists to understand how such tumours are still able to survive and grow, and to find new ways to block their growth. Results from this research should reveal new ways to combat drug resistance.