The NHS is failing to detect about 1,100 cases of bowel cancer a year in England because diagnostic services are so short-staffed, according to analysis by Cancer Research UK.

The charity has said people’s health may suffer if the disease has progressed to a later stage as a result of going undiagnosed. It said pledges to diagnose more cancers earlier might not be delivered.

Cancer Research UK said that a lack of radiographers, radiologists and endoscopists meant hospitals could not keep up with the growing number of people with suspected cancer being referred for tests.

About one in 10 such posts are lying vacant.

Sara Hiom, the charity’s director of early diagnosis, said: “The UK’s bowel cancer screening programme is very effective at detecting cancer early. But we’re concerned that NHS staff shortages are having a direct impact on the ability to diagnose more patients at an early stage, something the government committed to doing last year.

“People shouldn’t be slipping through the net.”

Cancer Research UK is concerned that as many as 1,100 people a year in England with bowel cancer are not being picked up because the NHS there used a higher threshold than Scotland in screening for the disease using the faecal immunochemical test.

In Scotland those whose testing shows they have 80 micrograms of haemoglobin per gram of faeces are referred to have a colonoscopy to determine if they have bowel cancer.

In contrast, in England only those with 120 micrograms go on to have further investigation. That is despite research showing that the lower the threshold, the more cases are detected and thus lives are saved.

The charity said: “This is where patients are missing out in potentially life-saving early diagnoses, largely due to a lack of specialist staff.”

It said that if the NHS in England used the same lower threshold for deciding on referrals then it would undertake 2,000 more endoscopies a month but would detect 1,100 more cases a year.

Dr Lisa Wilde, the director of research and external affairs at Bowel Cancer UK, said: “We know that the biggest constraint to increasing the sensitivity of England’s bowel cancer screening test is a lack of NHS workforce. Bowel cancer is the UK’s second biggest cancer killer but it doesn’t need to be: it is treatable and curable especially if diagnosed early.”

Bowel cancer screening starts at 50 in Scotland. It begins at 55 in England, though the NHS has pledged to reduce it to 50 at some point in the future.

An NHS spokesperson said: “The NHS has already introduced a new and more accurate way to test for bowel cancer that will catch 1,500 more cancers a year at an earlier stage and will save thousands of lives, alongside other important improvements through the NHS long-term plan, including lowering the bowel screening age to 50 and improving the sensitivity of the screening test.”

Prostate cancer has overtaken breast cancer as the UK’s most commonly diagnosed form of the disease, according to the most recent annual cancer registration figures published on Monday.