Ageism in the NHS is stopping some older cancer patients getting the best treatments, according to a new survey of doctors.
Nearly half of specialist cancer medics polled by Macmillan Cancer Support said age discrimination is preventing older cancer patients from getting the best treatments.
And this this could be a factor in Britain having some of the worst cancer survival rates in Europe for older people, the charity said.
Macmillan argued that patients' overall physical and mental wellbeing should be assessed when considering cancer treatment to ensure treatment decisions are not based on age alone.
The charity's chief executive Ciaran Devane said the concerns flagged up in the survey "mustn't be ignored" and staff should be given the appropriate time and training to carry out a proper assessment.
Otherwise "some patients will be unfairly written-off as 'too old' for treatment."
Mr Devane warned the problem could get worse as the number of older people aged 65 and over living with cancer in Britain is set to rocket from 1.3 million to 4.1 million in the next 20 years.
National Cancer Director Professor Mike Richards accepted there was a "significant problem" but insisted it was not done intentionally.
He said: "Regrettably, yes I do recognise that it is a significant problem that we see patients too often are assessed on the basis of their age rather than their fitness.
"For some people, really intensive treatments are not going to be appropriate, they wouldn't be able to withstand that."
Health Secretary Jeremy Hunt added: "It is shocking and wrong to deny people treatment just because of their age, which is why we have made it illegal.
"However, we agree that more still needs to be done to improve treatment for cancer patients over 70."