A life-prolonging new prostate cancer pill was officially launched in the UK today, but is yet to be made widely available to NHS patients.
Abiraterone acetate, marketed under the trade name Zytiga, has been shown to extend the lives of men with advanced prostate cancer.
It received a European Union (EU) licence two weeks ago, making it a legal medicine in the UK, but in practice only became accessible to patients today.
The drug works by blocking the generation of testosterone in all tissues, including cancer tumours. The male sex hormone fuels the growth and spread of prostate cancer.
A Phase III trial of 2,000 men with advanced disease showed that patients given the one-a-day pill lived 15.8 months on average compared with 11.2 months for those taking a placebo "dummy" drug.
Abiraterone was developed by British researchers at the Institute of Cancer Research (ICR) and the Royal Marsden Hospital.
Professor Alan Ashworth, chief executive of the ICR in London, said: "This drug will make a significant impact on the treatment of men suffering advanced prostate cancer.
"Abiraterone acetate gives doctors another important treatment option and we hope that it will play a part in one day turning prostate cancer into a chronic, rather than life-threatening, disease."
Professor Johan de Bono, from the ICR, who co-led the Phase III trial, said: "There are only a small handful of drugs available that can extend life for men with advanced prostate cancer.
"Clinical trials have proven that abiraterone acetate can not only prolong life, but in some men it can improve their quality of life.
"This offers hope to the thousands of men each year whose cancer stops responding to standard hormone treatments and chemotherapy."
Charities said it was important for the National Institute for Health and Clinical Excellence (Nice), which vets new treatments in England and Wales for cost effectiveness, to assess the drug.
A positive verdict from Nice would pave the way to the drug being widely available on the NHS.
Cancer Research UK chief executive Harpal Kumar said: "We're delighted to see that abiraterone is now available in the UK.
"It could help treat the 10,000 men diagnosed with aggressive forms of advanced prostate cancer in the UK each year.
"Nice must now decide as quickly as possible whether the drug should be made routinely available to all appropriate patients.
"Meanwhile, decisions about whether patients can be given this drug will have to be made locally or through the Cancer Drugs Fund."
Owen Sharp, chief executive of the Prostate Cancer Charity, said it was vital that both Nice and its Scottish equivalent, the Scottish Medicines Consortium (SMC), "swiftly" appraised abiraterone.
He said: "Abiraterone is one of the most important developments for some time in the treatment of men with an advanced form of the disease who are no longer responding to existing treatments.
"It is particularly encouraging to see that this drug can now be prescribed by doctors who think their patients will benefit from it.
"We hope that all local health providers will make funds available so that this drug can start to reach those men as soon as possible."
Each year around 37,000 men in the UK are diagnosed with prostate cancer and 10,000 die from the disease.