Patients hoping to access the government’s £50m cancer drugs fund could face difficulties depending on where they live, according to the Rarer Cancers Foundation.

The fund, which will act as an interim cash supply until a full fund is established in April, is designed to give patients access to non NHS-approved drugs.

An editorial in The Lancet medical journal said the fund is not the victory some charities and patient groups believe it is, and many patients could miss out. It described the fund as the product of “political opportunism”, which was “intellectually indefensible” unless emergency funds for other conditions like dementia and multiple sclerosis were also set up.

The criticism comes as the Rarer Cancers Foundation condemned the government’s refusal to confirm how much the eventual fund will be worth.

Before the election, David Cameron and Andrew Lansley said the full fund would be £200m and they said the cash would come from savings on the NHS’s national insurance bill to the Treasury.

But last month, Lord Howe said the £200m was an “aspirational figure”.

Today, the Department of Health said no final decisions on how much the cancer drugs fund will be worth would be made until the spending review in the autumn.

A report from the RCF today said 3,600 cancer patients could miss out on potentially life-extending drugs if the fund is not set at £200m a year.

The cancer drugs fund will pay for medicines that can extend life by a few months or improve quality of life but which may have been rejected by the health watchdog as too expensive.

It will also cover drugs currently used off-label by clinicians to treat conditions not covered by the medicine’s licence, or those which have yet to be appraised by NICE.

Today’s RCF report said making every cancer treatment available that clinicians believe their patients should have will cost an extra £175m to £330m per year.

A DH spokeswoman said it would try to ensure the maximum possible benefits for patients.