THOUSANDS of breast cancer patients could benefit from a drug already proven to treat lung tumours.

As The Sun reports, scientists have begun human trials after the treatment was found to kill breast cancer cells in mice.

The drug, crizotinib, targets a genetic defect that is found in around 7,000 breast cancer patients in the UK each year.

It is already used to treat non-small cell lung cancer by shrinking tumours.

Medics hope it can now be “repurposed” for women with the gene-related form of the disease.

Baroness Delyth Morgan, of charity Breast Cancer Now, called the discovery “extremely exciting”.

The new approach targets cells with faulty versions of a protein called E-cadherin.

This protein helps to bind healthy cells together but when defective it causes cancer cells to grow and divide abnormally.

E-cadherin defects occur in 13 per cent of all breast cancer cases and in up to 90 per cent of certain breast cancers.

Laboratory experiments at London’s Institute of Cancer Research found crizotinib killed cancerous breast cells without harming healthy ones.

The ICR’s Professor Chris Lord said: “These are hugely promising laboratory findings and we’re very keen to learn whether this drug really works as a treatment for women with breast cancer.

“It’s an approach worth pursuing. We’re very enthusiastic about the prospect of applying our results in clinical trials.”