A new breast cancer test which predicts the likelihood of cancer recurring could prevent thousands of women from undergoing unnecessary chemotherapy, its makers said.

The Oncotype DX test will benefit some of the 45,000 women diagnosed with breast cancer each year in the UK, according to molecular diagnostic company Genomic Health.

It creates “individualised tumour profiles” and provides personalised treatment decisions for patients and doctors, a spokesman for the company said.

The test, which can only work for women with a specific type of breast cancer, involves the examination of genes taken from a sample of a tumour removed during surgery.

The spokesman said: “In patients with newly diagnosed oestrogen-positive, node-negative breast cancer – which affects approximately half of women with breast cancer – chemotherapy is only beneficial in some patients.

“At the moment, doctors use measures such as tumour size and grade to determine whether to treat women with chemotherapy after surgery, typically deciding to use it in around half of cases.

“However, studies show that when doctors use the Oncotype DX test, they change their minds on use of chemotherapy in up to 34 per cent of cases.

“In approximately 24 per cent of cases, doctors decide not to prescribe chemotherapy after all, saving women from unpleasant side-effects of chemotherapy.”

“In 10 per cent of cases, doctors using the test realise that chemotherapy is actually needed when previously they thought hormone therapy alone would be sufficient.”

He said the test, which is not available on the NHS and costs about £2,500, has been validated in 13 studies of 4,000 patients.