One in five breast cancer patients in the UK may be able to benefit from a new drug designed to treat genetic forms of the disease.

A study carried out by researchers from the Wellcome Trust Sanger Institute led to the discovery that many more women than was previously thought are likely to respond positively to biological therapies or PARP inhibitors, such as olaparib, which is already available on the NHS for the treatment of ovarian cancer.

Initially, scientists thought only patients with faulty BRCA genes triggering the onset of their breast cancer would benefit from these drugs, but the new research found that as many as 20 per cent of individuals with the disease could see their symptoms lessened and potentially even cured thanks to PARP inhibitors.

The study saw doctors analysing the genetic make-up of 560 patients' breast cancer, finding that many samples shared a very similar biological structure with those attributed to BRCA anomalies.

Currently, many women found to have this genetic fault choose to undergo a preventative mastectomy, but the discovery that biological therapies such as olaparib could be used to treat them without the need to lose their breasts could change the lives of thousands of women each year.

Clinical trials are now being planned to assess the full effects of olaparib on treating different forms of breast cancer, but scientists are hopeful that this, or similar biological therapies, could help to save the lives of many women in the future.

The early results have been hailed as "a revelation" by Baroness Delyth Morgan of the charity Breast Cancer Now.

She added: "We hope it could now lead to a watershed moment for the use of mutational signatures in treating the disease."

Meanwhile, Professor Ruth Plummer, a Cancer Research UK clinician at the Northern Institute for Cancer Research, commented: "Research like this is incredibly important in helping as many patients as possible benefit from new treatments.

"Similar signatures have also been found in ovarian cancer, suggesting that it isn't only people with faults in their BRCA genes who could be treated with these drugs."