SCIENTISTS have identified genetic changes that may predict the likelihood of breast cancer relapse.

They studied tumour samples from patients taking aromatase inhibitor, a type of hormone therapy, for up to two years.

Samples were taken before the therapy started, within the first few weeks and after four months of treatment. Researchers found the therapy almost immediately triggered changes in genes that were switched on in the tumours.

Chemical signatures were absent in tumours that developed resistance to treatment.

But they were present in those that had started growing again after initially shrinking.

The differences were noticeable in the first weeks of therapy. Dr Andy Sims, of the University of Edinburgh, said it could help to identify those at risk so they can be given alternative treatments.

Dr Simon Vincent, of Breast Cancer Now, which helped fund the study, added: “This is promising. Drug resistance is a major hurdle we must overcome if we are to finally stop women dying from breast cancer.”