One of the great frustrations for many people, and their doctors, is vague tummy discomfort or bloating.

Most often, there are relatively benign reasons for these symptoms.

But how can know if there’s something more serious going on?

You’ll probably get sent for blood tests.

And that’s when things can become complex and potentially serious … or could just be easily explained as you being rundown.

Results often mixed or misleading

The results might be a mixed bunch. Inflammatory markers might suggest diverticulitis … or gallstones.

Raised platelets, which are immune cells, suggest an infection, but can also indicate inflammation.

Abnormal ferritin (iron levels) and anaemia suggest your diet needs attending to … eat some steak.

All these symptoms can be tied together and dealt with as straightforward digestive and nutritional issues.

Sometimes there’s a curve ball

The biggest immediate worry – what complicates the situation – is low albumin, a protein responsible for transporting vitamins, enzymes and hormones throughout your body.

It can indicate liver or kidney issues, or something else.

But these aren’t showing up yet?

Your GP has to tease all this out. What’s next? Scans?

What he or she is potentially missing here is the significant risk that you’ll be diagnosed with cancer within a year.

The predictive value of blood tests

Until now, the predictive value of routine blood tests for cancer was only guessed at.

Now, scientists from University College London (UCL) have only just discovered that, “in 19 commonly used blood tests, abnormal results were linked to a higher risk of being diagnosed with cancer within a year”.

The results of these routine blood tests “could be used to speed up cancer diagnosis among people with stomach pain or bloating”.

The study looked at data from more than 400,000 people aged 30 or older in the UK who had visited a GP due to stomach pain.

It also investigated more than 50,000 people who had visited their GP due to bloating.

Two-thirds of this group had blood tests following their appointment.

If these abnormal results were taken into account, there’d be a 16 per cent increase in the number of people with undiagnosed cancer given an urgent referral.

That’s compared to assessment based on symptoms, age and sex alone.

More people urgently referred for cancer

The researchers say this translates as an extra six people with undiagnosed cancer being urgently referred out of 1000 people who had visited the GP with stomach pain or bloating.

That’s on top of 40 people per 1000 with cancer being urgently referred already, without using blood test results.

Lead author Dr Meena Rafiq, of the UCL Department of Behavioural Science & Health, said:

“Our study suggests we can improve cancer detection with blood tests that are already available and that are routinely given to patients with non-specific symptoms whose cause is unclear.”

She said this could be “an efficient, affordable way to improve early cancer diagnosis”.

In some cases it could increase the likelihood of successful treatment.

However, she said it may be “challenging for GPs to interpret a range of blood test data”.

The study suggests a need “for an automated tool that could assess cancer risk based on multiple variables”.

The study  

The UCL team used patient data from the Clinical Practice Research Datalink. This was collected from a network of GP practices across the UK between 2007 and 2016.

The researchers found that one in 50 (2.2 per cent) people who went to the GP reporting stomach pain were diagnosed with cancer over the next 12 months.

The same proportion (2.2 per cent) of people reporting bloating were also diagnosed with cancer within a year.

In the study sample, the researchers found that, among people aged 30 to 59 years with abdominal pain or bloating, anaemia, low albumin, raised platelets, abnormal ferritin, and increased inflammatory markers “strongly predicted a risk of undiagnosed cancer”.

Dr Rafiq added: “Half of all people with as-yet undetected cancer will first go to the doctor with vague symptoms that can be challenging to diagnose.”

The study also showed which types of cancer were most common for people with these symptoms and how this varied depending on age and sex.

Overall, bowel cancer was most common. This was followed by prostate and pancreatic cancer in men.

In women bowel cancer was followed by breast and ovarian cancer.