The drug may extend life for some women
A new drug has been licensed to treat UK patients with advanced breast cancer that has begun to spread.
However, patients may find problems getting Avastin, as the NHS drugs watchdogs have yet to consider whether to sanction its use.
The drug is designed to be used in tandem with another chemotherapy agent, paclitaxel.
Avastin, which works by starving cancer cells of a blood supply, has previously been used to treat bowel cancer.
However, the drug was rejected for NHS use in England and Wales for that purpose last year.
The National Institute for Health and Clinical Excellence (NICE) ruled that it was not cost-effective.
In trials, breast cancer patients who took Avastin and paclitaxel went an average of 13 months without their cancer growing, compared with an average of 6.7 months for patients who took paclitaxel alone.
Professor David Miles, a consultant medical oncologist at the Mount Vernon Cancer Centre, Middlesex, said: "This provides some hope for the 13,000 patients a year that are told the devastating news they have metastatic breast cancer which cannot be cured with surgery.
"It is an important step forward to have discovered another targeted treatment which can inhibit the growth of breast cancer and as a result increase significantly the time that patients' breast cancer is controlled."
Dr Emma Pennery, a nurse consultant at the charity Breast Cancer Care, said women with secondary breast cancer would welcome any treatment that could potentially slow down the progression of their disease.
"This announcement means that there is now another treatment option available, adding to the growing range of targeted drugs for breast cancer."
Dr Pennery called on the National Institute for Health and Clinical Excellence (NICE) and the Scottish Medicines Consortium to appraise the drug as soon as possible.
Dr Sarah Rawlings, of the charity Breakthrough Breast Cancer, said: "The development of targeted therapies like this is an important step forward in cancer treatment.
"Avastin is an additional treatment option that will be welcomed by women with metastatic breast cancer, although it's important to remember it might not be suitable for everyone.
"All breast cancer treatments will have risks and benefits so it is vital women have all the information they need to make informed decisions about their treatment options.
"Any woman concerned should discuss this with her doctor."