Older people are being denied vital surgery for cancer, hernia repairs and joint replacements because the NHS imposes "cutoffs" for treatment based on age discrimination, a report has warned.

Health professionals can be too quick to decide against offering surgery because of "outdated assumptions of age and fitness", according to the study by the Royal College of Surgeons, the charity Age UK and communications consultancy MHP Health Mandate. Doctors and surgeons should stop using chronological age to assess suitability for a procedure and instead use their "biological age", or overall health, because growing life expectancy and the increasingly good health of senior citizens make birth date alone redundant as the deciding factor, it says.

The study found that while people's health needs increase as they grow older, rates of planned surgery for some common conditions among older people steadily decline. "The gap between the increasing health need and access to surgery means many older people are missing out on potentially lifesaving treatment," concludes the study, which details the variation by age group in patterns of treatment for eight types of surgery.

"It is alarming to think the treatment a patient receives may be influenced by their age," said Professor Norman Williams, president of the Royal College of Surgeons. While there are often valid explanations why older patients decide not to have surgery or are recommended non-surgical treatment, he said: "The key is that it is a decision based on the patient rather than how old they are that matters."

The report details "barriers" to older people receiving surgery, including that "some symptoms can be dismissed as an inevitable part of ageing rather than a potential sign of ill-health. This can mean a disease is at a more advanced stage by the time they are diagnosed, ruling out surgical treatment". Equally, some older patients' overall health may mean the risks of having a procedure outweigh the benefits.

The report takes doctors and surgeons to task for letting outdated attitudes influence their decision-making about older people's eligibility for surgery. "The clinical benefit of providing treatment may be questioned when relative life expectancy is shorter," it says.

Communication with older patients to discuss risks and benefits can be limited or ineffective. Conflation of chronological and biological age "means decisions may not always be made on the basis of a comprehensive and objective assessment but on a series of assumptions about fitness in older age".

While the incidence of breast cancer is highest in women aged 85 and over, surgery peaks among those in their mid-60s and declines sharply from 70. Similarly, rates of surgery for prostate cancer, which kills 10,000 men a year, do not reflect the number of older men being diagnosed with the disease.

Life expectancy is 78 for men and 82 for women. Yet men and women who need a new hip or knee, usually owing to arthritis or a fall, are most likely to get one up to the age of 75 but less likely to do so after that, even though National Institute of Health and Clinical Excellence (Nice) guidelines to the NHS say age should not influence whether someone has that surgery, given its benefits.

Joint replacements appear to be increasingly restricted as the NHS rations treatments in an attempt to save £20bn by 2015. That financial pressure could mean older people are disproportionately affected by this trend in coming years, the report warns.

The gap between the number of people living with a condition or health need and the rates of surgery among older people should make surgeons and other health professionals rethink their attitudes to treatment for senior citizens, said Michelle Mitchell, charity director general at Age UK. "When it comes to people's health their date of birth actually tells you very little. A healthy 80-year-old could literally run rings round someone many years younger who does not share the same good health.

"Yet in the past too many medical decisions we believe have been made on age alone with informal 'cutoffs' imposed so that people over a certain age were denied treatment."

Such practices are now illegal. In June, the government said denying drugs or treatments on the grounds of age would be outlawed from this month, meaning older people may be able to sue the NHS to challenge decisions they feel are discriminatory because of their age.

"A new legal framework to outlaw age discrimination in the NHS cements our moral duty of care to older patients and sends a clear signal to the NHS to deliver the best care and support to every patient in line with his or her needs," the report notes.

The Department of Health said the NHS should not deny patients treatment because of their age. "There should be absolutely no place in the NHS for assumptions about entitlement to treatment that are based on age or any other form of unjustified discrimination," said Dan Poulter, the health minister. "All patients should be treated as individuals, with dignity and respect, and receive care that meets their healthcare needs irrespective of their age.

"The government is committed to providing dignity in elderly care, and at the beginning of October we introduced an age discrimination ban, which means that all patients will receive a more personalised care service, based on their individual needs, not their age."