Around 10,000 women a year in the UK could benefit from a change in how doctors issue breast cancer drugs, research suggests.
Currently, women who have inherited faulty genes linked to breast cancer – such as the BRCA1 or BRCA2 genes – are treated using biological therapies, also known as “PARP inhibitors”.
But new research from the Wellcome Trust Sanger Institute suggests these drugs may also effectively treat women whose breast cancer is not linked to the faulty genes.
The study suggests one in five breast cancer patients could benefit from receiving this form of targeted therapy.
Breast cancer is the most common cancer in the UK, affecting nearly 55,000 women a year.
Globally it accounts for nearly 1.7 million cancer cases. Between 1% and 5% of breast cancer cases are due to inherited mutations in BRCA1 or BRCA2 genes.
Drugs called PARP inhibitors have been designed to specifically treat tumours with faulty BRCA1 and BRCA2 genes in breast and ovarian cancers, and their use against prostate cancer is currently being investigated.
In the latest study, researchers analysed the breast cancer gene sets of 560 patients and looked for every single type of mutation possible.
The team identified patterns of mutations – calle mutational signatures – in the tumours, which were similar to people who have mutations in the BRCA1 and BRCA2 genes.
Scientists discovered that many breast cancer patients had mutational signatures that were identical to people with faulty BRCA1 and BRCA2 genes, even though they had not inherited the mutations.
The results suggest that roughly one in five breast cancer patients could benefit from existing PARP inhibitor treatments, the researchers said.
This would need to be tested through a clinical trial, with participants being selected based on the mutational signatures of their tumour.
The full results are published in the journal Nature Medicine.