The NHS has a finite pot of money for treatments
Drugs which give terminally ill patients a few extra months to live have a better chance of being approved on the NHS under new rules.
The National Institute for Health and Clinical Excellence (NICE) is to extend the threshold at which the drugs are deemed cost-effective.
But this will only be in certain circumstances for instance in people who have less than two years to live.
The rules affect decisions for England, Wales and Northern Ireland.
It is thought one or two treatments a year will be affected by the change.
The charity Macmillan Cancer Support estimated 10,000 cancer patients a year could benefit.
The announcement follows a five-week public consultation and will come into effect in time for the January meetings of Nice advisory committees.
It will impact decisions made around treatments offering survival benefits for terminal illnesses affecting small numbers of patients and which are more expensive than would normally be considered acceptable under Nice guidelines.
Any treatment to meet the criteria must be for patients with a short life expectancy, normally less than 24 months.
There must be sufficient evidence that does extend life, usually at least an additional three months, compared with current NHS treatment.
And it must have a cost-effectiveness ratio higher than the £30,000 cut-off normally used by NICE to determine good use of NHS resources.
There must also be no alternative treatments with similar benefits available on the NHS.
In August patients with advanced kidney cancer were denied access to treatments proven to extend life by five to six months because they were deemed not to be value for money.
Andrew Dillon, NICE chief executive, said they were asking their advisors to give "greater weight" to life-extending treatments when people do not have long to live.
"The Institute is also conscious of its responsibility to support the development of novel treatments for smaller patient groups that provide innovative benefits over and above existing NHS care."
Rachel Rowson, policy manager at Macmillan Cancer Support, said they had been campaigning for the rule change.
"We hope this will now mean that people with rarer cancers and those at the end-of-life stage get access to the drugs they need on the NHS."
Stella Pendleton, executive director of the Rarer Cancers Forum, said the decision could benefit many thousands of patients.
"However, there are many treatments which can never be assessed by NICE in the first place because of the rarity of the cancers they treat.
"Ministers need to explain how these patients can receive the life-sustaining treatments they need without relying on top ups."