A Scottish government-funded study has found that a common test used to detect bowel cancer increases in accuracy when carried out twice, an approach researchers say has the potential to lower deaths from the UK’s second-most-deadly cancer.

A University of Edinburgh-led study found carrying out faecal immunochemical tests (FIT) – which detect low levels of blood in bowel movements – an extra time increases the accuracy of diagnosis of bowel cancer to almost 100%.

The researchers also say a two-test approach has the potential to reduce demand for colonoscopies.

Latest figures show 41.4% of colonoscopy patients in Scotland have been waiting 13 weeks or longer.

Bowel cancer is the fourth most common cancer in the UK and the second biggest killer of all cancers – more than 16,500 people die from the disease every year.

The Edinburgh team highlighted the importance of early detection of bowel cancer, as it is treatable and even curable if detected early.

Many people have symptoms of bowel disease like stomach pains, changes to their normal bowel movements or losing weight without trying to – but none are specific to bowel cancer which can lead to invasive investigations that they may not need.

The study showed the use of one test correctly detected 84.1% of bowel cancer cases, while two FIT tests correctly detected 96.6% of bowel cancer cases – a 50% reduction in missed cancer cases. The two tests were carried out with a median time between each test being 13 days to pick up on any variation.

Miss Farhat Din, Reader at the University of Edinburgh and Consultant Surgeon at the Western General Hospital, said:

“Our study highlights how to maximise use of FIT in symptomatic patients. Use of two FIT tests will miss less bowel cancer with a positive impact on patient care.

“Locally, implementation of the double-FIT strategy has led to a reduction in endoscopy without adversely affecting cancer detection rates.”

The study was funded by the Scottish government, Scotland’s Chief Scientist’s Office and Cancer Research UK Scotland Centre and involved two groups of NHS Lothian patients which had been urgently referred to the Edinburgh Colorectal Surgery Unit.

In 2020, Public Health Scotland reported a five-year low of bowel cancer detection via screening for people aged 50-75 years old, citing the pausing of screen services among the reasons for decreased cancer diagnoses during the pandemic.

Current guidance uses a one-test approach to determine which patients are indicating a high risk of bowel cancer and should be prioritised for further investigations.

Researchers explain that, given the increasing use of FIT as the first investigation for suspected bowel cancer across the UK, it is important to find best practice to avoid missing patients with undiagnosed bowel cancer.

The study also revealed that 16.8% of the patients who completed two tests had enough variation in their test results to change the original management plan. Experts say this was irrespective of a significant bowel condition, highlighting the benefits for treatment beyond the increased cancer diagnosis rates.

The workload implications of increasing the number of FIT tests were found by the study to be low, as those patients with two negative tests may be given alternative management plans that place a lower demand on healthcare staff.

Patients with two negative FIT tests have a very low underlying risk of bowel cancer (0.17%) meaning they may not need to undergo further tests.

With double testing reaching almost 100% accuracy in detection of bowel cancers, researchers said balancing the ‘modestly increased workload’ against improved diagnoses and reduction in missed pathology means the rolling out of double testing may be worthwhile.

Read more: Aberdeen team to repurpose COVID test technology; Radiotherapy optional for older breast cancer patients; Pandemic cancer care extended; Cervical cancer unit to treat patients in 30 minutes; Pandemic impact on cancer incidence in Scotland

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