It is not a cure but temporarily stops progression of the disease for women with advanced cases of breast cancer who test positive for the protein HER2.

Maker GlaxoSmithKline estimates its drug will help 2,000 women a year in the UK.

These are patients who have been treated using other frontline therapies including surgery, chemotherapy and radiotherapy and whose disease has stopped responding to another drug, Herceptin.

Trials show the drug gives patients a breathing space of 27 weeks on average before the disease progresses further. It costs £1,600 for four weeks and targets cancer by smuggling itself into cancer cells and blocking them from sending out signals telling them to divide and grow.

One in four women with breast cancer contract HER2-positive disease which is faster-growing and has a poorer prognosis.

It is only available at the moment to suitable patients taking part in trials. The National Institute for Clinical Excellence is yet to assess the drug, also known as Tyverb, to see if it can be provided on the NHS.

Cancer specialist Jo Dent, who is treating Kim Robson at the infirmary in Huddersfield, said it was not a cure but offered benefits to patients who were suitable. Ten women had so far received it at the hospital and Kim had done "incredibly well".

She added: "It's not a miracle drug but it can certainly be of benefit in halting the progression of disease."

Pamela Goldberg, chief executive of the Breast Cancer Campaign, said: "Tyverb is a new way to treat breast cancer as it specifically targets the receptors responsible for tumour growth; just one of the many new breast cancer treatments in the pipeline that will provide tailored treatment for the patient.

"However, it is important to emphasise that it is not a new wonder drug suitable for all breast cancer patients."