NHS drugs advisers have reversed their proposal to block a drug for people with asbestos-related cancer.
Mesothelioma most often attacks the lungs
The National Institute for Health and Clinical Excellence had said Alimta (pemetrexed disodium) should be used only in new or ongoing clinical trials.
But manufacturers Eli Lilly appealed against the guidance, covering England and Wales, and a new NICE draft says it can be used for advanced mesothelioma.
Campaigners say they are delighted. Final guidance is due in September.
About 4,000 people a year develop the cancer, mainly among populations who were in manufacturing industries.
The cancer is nearly always terminal, but the drug can help extend patients lives.
NICE originally said Alimta should only be recommended for use in new or ongoing clinical trials.
But under the revised guidance, Alimta is recommended for patients who are able to carry out day-to-day tasks but whose cancer is advanced and where surgery is inappropriate.
The drug is used to treat mesothelioma, a type of cancer which most often affects the lining of the lungs and is mainly linked to asbestos exposure.
If there are no appeals against the new guidance, it will be issued to the NHS in the next few months.
Dr Mick Peake, a consultant physician and vice chairman of Mesothelioma UK, said "This is absolutely excellent news for all those patients suffering from this dreadful disease.
"Pemetrexed is one of the very few treatments for which there is good evidence of benefit."
NICE said during the consultation it emerged that costs could be reduced by shorter treatment cycles and lower doses.
Dr Gillian Leng, NICE implementation director and executive lead for the guidance, said: "Our initial review of the evidence available on pemetrexed disodium suggested that it was insufficient to demonstrate that the drug was better than other, far less costly medicines.
"However, a number of significant factors have become apparent, which, taken together, have enabled the independent appraisal committee to recommend pemetrexed disodium as a treatment option for the majority of people with the cancer."
Dame Helena Shovelton, chief executive of the British Lung Foundation,
said: "The UK is facing an epidemic of mesothelioma in 2011 - 2015 as people exposed to asbestos in the 1960s and 1970s are diagnosed with the disease.
"Already more than 2,000 cases are identified each year. We strongly believe that everyone with this deadly chest cancer should be able to benefit from the widest possible range of treatment options and drug therapies."