Breast cancer patients most likely to benefit from hormone therapy can be identified quickly from tissue samples, research shows.
Scientists can accurately predict who is likely to respond to the medicine within two weeks of treatment, the study found.
They say it could help to personalise treatments for women with breast cancer to maximise their chances of survival.
A team led by the University’s Edinburgh Cancer Research Centre investigated how patients with breast cancer responded to a class of drugs called aromatase inhibitors.
They checked which genes were active in tissue samples from breast cancer patients who were being treated with an aromatase inhibitor called letrozole.
They compared the levels of thousands of genes in samples that were collected from patients before and during treatment.
The researchers were looking for patterns of gene expression that might be linked to whether or not the treatment is having an effect.
We’re hopeful these findings could translate into a robust clinical test given to all women in the appropriate category to accurately predict if they will respond to treatment.
They found that four particular genes were expressed at different levels in tissue samples from patients who had responded well to the therapy compared with those who had not responded.
This genetic profile was able to accurately predict which women were most likely to respond to treatment in 96 per cent of cases.
The researchers confirmed their findings in a blind test of samples from patients treated with anastrazole, a different type of aromatase inhibitor.
This research brings hope that we will one day be able to quickly rule out those patients who are not likely to respond to hormone therapy so that they can be given alternative treatments. Selecting the right treatment for patients as early as possible is crucial to minimise the risk of the cancer becoming more aggressive and spreading to other parts of the body.
Aromatase inhibitors work by blocking the production of the hormone oestrogen. They are given to patients with breast cancers that are positive for the oestrogen receptor, called ER positive breast cancer.
About 70 per cent of breast cancers are ER positive but only around 30 to 50 per cent of these patients will respond to aromatase inhibitors.
The study is published in the Journal of Clinical Oncology. It was funded by Breakthrough Breast Cancer.