More than 80% of NHS hospitals in England are failing to test bowel cancer patients for the genetic condition Lynch syndrome, according to the charity Bowel Cancer UK.
The condition increases the risk of bowel and other cancers.
Bowel Cancer UK estimates that 166,000 people in the UK are unaware that they have the condition.
An NHS England spokeswoman said there are clear guidelines about when it is appropriate to test for Lynch syndrome.
Testing for the syndrome can guide the treatment of the patient and indicates whether their families are at risk.
Children of people with the condition have a 50/50 chance of developing it.
The charity says it is important to find out whether patients have Lynch syndrome, because some chemotherapy drugs are ineffective for them.
And if other family members find they have the syndrome then it enables them to take steps to reduce their risk of bowel cancer, or be diagnosed at an earlier stage when it is easier to treat.
Teenage cancer fundraiser Stephen Sutton, who died of bowel cancer at 19, had Lynch syndrome. His father had twice battled bowel cancer.
When Stephen presented with similar symptoms he was told he was too young to get the disease, delaying his diagnosis for six months.
- Lynch syndrome (LS) is also known as hereditary non-polyposis colorectal cancer (HNPCC)
- It is caused by an alteration in a gene called a mismatch repair gene
- LS doesn't cause any symptoms
- LS increases your lifetime risk of bowel cancer by up to 80%, and also of developing many other cancers including ovarian, stomach and womb
- If your family has a history of developing these cancers when they are under 50 years old, it is possible they have the altered gene that causes LS
- Knowing about the risk and having regular screening may help prevent some cancers. It may also help other cancers be found in the early stages, when they are more likely to be curable
- People with LS are screened every two years – some people with LS even remove part of their bowels or wombs to pre-empt potential cancers
The National Institute for Health and Care Excellence (NICE) guidelines recommend testing all bowel cancer patients for Lynch syndrome at the time of their diagnosis.
A Freedom of Information request by the charity found that 83% of NHS hospitals in England are not testing for the condition.
They said that 91% of those hospitals cited financial reasons as the main barrier and 61% said staff resources were a problem.
One hospital trust said: "The main barriers have been, and remain, financial and staff resources. NICE produce guidance but the government do not provide the funding for the implementation of the guidance. It is a recurring theme and, with the increasing use of genomic medicine, is a major problem for pathology departments."
But the charity says the cost of the test is small compared to the cost of treating patients for bowel cancer, which they say is around £25,000.
- Cancer gene test 'would save lives'
- Cancer model research helps pinpoint risk, says Cardiff Uni scientist
Deborah Alsina, chief executive of Bowel Cancer UK and Beating Bowel Cancer, said: "The price of testing for Lynch syndrome is peanuts – only £200 per patient. Clinical Commissioning Groups (CCGs) need to loosen the purse strings as the price of testing for Lynch syndrome far outweighs the cost of treating bowel cancer patients.
"A lack of funding and resources from CCGs means that hospitals' hands are tied. Until these issues are being addressed, generations of families will continue to be devastated by cancer and lives will be needlessly lost."
Their campaign is being backed by TV presenter Matthew Wright, whose family has a history of bowel cancer.
"At the time of my father's death, my family and I were told about Lynch syndrome and the 50% chance that me and my sister could have it too. Although I was convinced I had it, it was only until five years after my father's death that I found out I didn't have Lynch syndrome," he said.
"We need to address this crisis of families not being tested for Lynch syndrome. We have the right to know if we have a higher risk of bowel cancer, the disease is deadly and it can't keep devastating families like mine."
Annika Perdomo, who is 53 and from Warwickshire, has Lynch syndrome – she was diagnosed with bowel cancer at the age of 49.
"The saddest thought for me is the fact that there's a 50/50 chance of my 10-year-old daughter having Lynch syndrome too. She will be tested when she reaches the age of maturity, as will my nephew and nieces.
"But the major difference for them is that they will be screened and monitored from an early age. Unlike me, any symptoms they may be experiencing however young they are at the time, their GP will at least sit up and listen.
"Unfortunately, three of my siblings have since tested positive with the genetic condition. Lynch syndrome is very scary due to the fact that tumours can grow more rapidly.
"It was for this reason that I opted for preventative surgery two years ago by having a full abdominal hysterectomy to rid the chance of me ever having an endometrial cancer. My sister also has Lynch syndrome and has been through the same preventative surgery."
An NHS England spokeswoman said: "There are clear NICE guidelines for when it's appropriate to test for Lynch syndrome that we expect NHS providers to follow but the quality of cancer care is always improving and the NHS is catching more cancers early with 7,000 more people surviving cancer compared to just three years ago."