Claims by Macmillan Cancer Support that delayed assessments for a disability benefit have left at least 4,500 cancer patients waiting six months or more have been questioned by welfare officials.
The Department for Work and Pensions said the charity's survey results are "at best to be treated with extreme caution" because it involved only 210 patients.
Official statistics on waiting times are still being compiled.
Macmillan's report is based on a very small sample size using simplistic calculations to produce results, which at best should be treated with extreme caution.
Claims for terminally ill people are fast-tracked using 'special rules' under Personal Independence Payment and statistics show over 99% of people with terminal illnesses who have applied have been awarded the benefit. That means over 10,000 terminally ill claimants are now receiving PIP.
We have been working with Macmillan and they have acknowledged that improvements to the system have already been made.
PIP replaces the outdated Disability Living Allowance which was introduced over 20 years ago.
It includes a new face-to-face assessment and regular reviews - something missing from the old system - to make sure support is better targeted at those who need it most.
More top news
The returns of Benedict Cumberbatch's detective and the X Factor judge were among 2014's most tweeted TV moments in a billion conversations.
A family has issued an appeal to help find their missing pet turkey - in case he gets gobbled up as someone's Christmas dinner.
The winner of X-Factor Ben Haenow has revealed how keen he is to have the Christmas number one.