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Poo tests: looking for cancer clues in poo

by Ethan Meyers | Analysis

28 November 2019

12 comments 12 comments

This entry is part 3 of 4 in the series Detecting cancer early

It’s a substance most people try not to think about. But it could be a vital tool when it comes to detecting bowel cancer early.

We need to talk about poo.

In diagnosing some cancers, poo has a particular advantage. Professor Chris Probert, a Cancer Research UK-funded bowel cancer expert at the University of Liverpool, explains why it’s such an important tool.

“For bowel cancer, where in the body is the action happening? It’s in the gut. And where are those chemicals that we want to detect most likely to go? In the stool.”

Current tests for bowel cancer screening already take advantage of this fact, using poo to look for early signs of bowel cancer.

“The beauty of looking at the faeces is that it’s right up against the cancer, making it very likely what you’re looking at came from that cancer,” says Probert. “Whereas if I find a compound in the urine, it may have been filtered from the blood, and excreted in the urine, having come from anywhere else.”

In other words, poo can provide very specific information about the state of someone’s gut.

Getting FIT

Until recently, faecal occult blood tests (FOBt) were used to screen for bowel cancer across the UK.

“The bowel cancer screening programme aims to find polyps, and because some polyps bleed, the detection is based on finding traces of blood in people’s stool.”

But this test has its problems.

  • It detects any blood, not just human blood, so results can be skewed by a person’s diet.
  • FOBt also require 6 samples (2 samples from 3 separate poos) to flag if more tests are needed.
  • The test also relies on technicians judging colour changes when the samples are processed, which can cause errors in how results are interpreted.

But as of June this year in England, September this year in Wales and in November 2017 in Scotland, FOBt has been replaced by a better test, the Faecal Immunochemical Test (FIT). Northern Ireland are still using FOBt, but the plan is to begin switching to using FIT in 2020.

And unlike FOBt, FIT only detects human blood, requires just one sample and uses an automatic analysis process that provides a number to indicate how much blood is in a sample.

Since FIT was introduced, more people in Scotland have taken part in bowel screening. It’s thought this could be because FIT is an easier test to complete

An expanding field

The recent switch from FOBt to FIT exemplifies the improvements made in using poo to detect cancer. But it’s not the only progress being made. Scientists are investigating if there are other cancer clues that can be picked up in poo samples.

For example, a Cancer Research UK-funded team at Cardiff University are exploring if detecting a certain safe strain of salmonella can help to locate polyps and help to pick up bowel cancer earlier.

Probert and his team are taking a different approach. They’re investigating if chemicals that come from the gut can help doctors detect the early signs of cancer, in a project called VODECA (Volatile Organic compounds for the DEtection of Colorectal cAncer).

The team detect volatile organic compounds, or VOCs (which are essentially odours), to see if any of them could help indicate if a patient has cancer.

VODECA – smelling the problem

Probert’s research started off as anecdotal evidence.

“Historically patients in my clinic have reported that when they’re unwell, they notice a change in what some may call bathroom odours.”

Gases from poo come from all sorts of places. Some come from diet, but other gases come from the chemical reactions taking place in our gut.

“We thought that these smells could be telling us something about the biology of the gut, and it might provide a useful signature.”

A few months ago, Probert’s team discovered that the molecules found in people with bowel cancer’s poo are different from those found in people without the disease. “This means that potentially, from a stool sample, you can get quite an interesting insight to what is going on in the gut.”

VODECA, though promising, is still in its early phases. But Probert can see this research working alongside FIT tests to aid early diagnosis.

“Early diagnosis might become a two-step analysis, where you look for things that bleed and then within the things that bleed you look for what is most likely to be cancer.”

And, the added benefit of using these VOCs for Probert is “it’s, quite literally, a lot cleaner to work with.”

“Nothing is insurmountable, but there is an aesthetic issue”

Studying the digestive system and what it produces is clearly rich with scientific capability to improve the early detection of cancer. But there’s an ongoing issue.

According to Probert, it’s quite hard to get people involved. “I know from my earlier research that if you just want a healthy volunteer to give you a stool sample for research, they are not as willing as someone who thinks it might be useful for them and understands the need to make a diagnosis for bowel cancer.”

Probert is optimistic about this problem, saying that more and more people are willing to donate poo samples, which is providing essential data for their research.

“People think nothing of giving blood samples, and I think with more time, it will become more mainstream to look at faecal samples too.”

Which can only be a good thing for detecting cancer earlier.

Ethan

Follow our early detection series to find out all the other ways – and bodily fluids – our scientists are looking for cancer in to detect it earlier and boost the chance of people surviving the disease.


    Comments

  • Diane ecker
    18 February 2023

    Great deal!!!

  • Ian McAlpine
    10 February 2020

    Good article. I had bowel cancer detected 3 years ago with the bowel screening test in Scotland. Very important to encourage people to do this test and catch and treat bowel cancer early.

  • Carole
    10 February 2020

    Helen Carter
    The very same for me did every test and nothing showed. Apparently it does not always show up. Then I had to redo the test and had cancer. Fortunately for me I had the operation and chemo and I am still clear 3 years on. I was told if I had left it any longer it would have not been a good result but I had had all the tests and had no symptoms. I was just very lucky. I am so sorry for your loss. Only 50 per cent of people take the test. Sebring you love.

  • Mervyn Amesbury
    8 February 2020

    I have done the’poo’ test 2 or 3 times, but I often wonder whether my behaviour as a blood donor might be a more sensitive test of occult blood loss. I give a ‘pint’ of blood every 3 months and obviously am checked for anaemia before giving. Would I be correct in thinking that this might give earlier warning of a problem than a poo teat every 2 years?

  • reply
    Katie Roberts
    11 February 2020

    Hi Mervyn,

    Thanks for your question about anaemia, blood tests and bowel screening.

    Different blood tests look for different things. Anaemia can be a symptom of bowel cancer, but it can also be caused by various other conditions, and not everyone with bowel cancer will be anaemic. The blood test before donating blood isn’t a good enough test for early signs of bowel cancer.

    The faecal immunochemical test (FIT) used during bowel screening specifically detects blood in your poo. This can be a sign of early stage bowel cancer in people who appear to have no symptoms.

    Thanks,

    Katie, Cancer Research UK

  • Frank Ball
    8 February 2020

    I had a cancer detected early by FOBt and had it removed 7 years ago. So for me this was a fantastic program and everyone needs to be encouraged to take part when the opportunity presents itself. This type of test is a life saver.

  • Susan Smith
    7 February 2020

    I had bowel cancer 2015. It was detected in a poo test and saved my life. It is important that people do the poo test when they are invited to

  • Helen carter
    6 February 2020

    Thank you for the information. I am sort to say that the poo screening tests are not at all accurate. My husband and I have always carried out these tests and until the last test we have both received normal results. The last screening my husband had came back with blood showing in the sample so he was requested to carry out. Repeat. This comeback normal . He had a rectal examination at our GP surgery no worries only piles or perhaps a polyp no need to worry. End of May 2019 he developed an accuse pain in left side. Went to GP thinking he had strained himself. Given blood tests endoscopy MR I scan CT scan and within two days diagnosed with inoperable bowel cancer. He died in under 4 months. He went from a lovely fit handsome 69 year old man to a shadow of himself. He died in front of my eyes Why was this cancer missed?

  • Antoinette Hasler
    6 February 2020

    Really informative article. Thank you.

  • Margaret Hook
    16 January 2020

    Thank you so much for this article about cancer and in particular bowel cancer. Actually knowing about these things is always good, trying to guess is not, so please keep reporting on cancer, I have had it three times so far, aged 89, very active so every grateful for any information you give. Incidentally I do not ‘live with cancer in my mind’ I rarely think about it at all and never think it might strike again. |Many thanks Margaret Hook

  • 4 December 2019

    Thanks for this. So useful

  • Tara Gipp
    4 December 2019

    Thanks for the great article. It would be interesting to see this expanded to pancreatic cancer,https://www.pancreaticcancer.org.uk/information-and-support/facts-about-pancreatic-cancer/signs-and-symptoms-of-pancreatic-cancer/

  • John Hunt
    28 November 2019

    I had a test a few weeks ago , it was one of those that’s advertised, £39 I think , it came back alright , should I have another couple to be sure , many thanks and keep up your fantastic work 👍 John Hunt .

    Comments

  • Diane ecker
    18 February 2023

    Great deal!!!

  • Ian McAlpine
    10 February 2020

    Good article. I had bowel cancer detected 3 years ago with the bowel screening test in Scotland. Very important to encourage people to do this test and catch and treat bowel cancer early.

  • Carole
    10 February 2020

    Helen Carter
    The very same for me did every test and nothing showed. Apparently it does not always show up. Then I had to redo the test and had cancer. Fortunately for me I had the operation and chemo and I am still clear 3 years on. I was told if I had left it any longer it would have not been a good result but I had had all the tests and had no symptoms. I was just very lucky. I am so sorry for your loss. Only 50 per cent of people take the test. Sebring you love.

  • Mervyn Amesbury
    8 February 2020

    I have done the’poo’ test 2 or 3 times, but I often wonder whether my behaviour as a blood donor might be a more sensitive test of occult blood loss. I give a ‘pint’ of blood every 3 months and obviously am checked for anaemia before giving. Would I be correct in thinking that this might give earlier warning of a problem than a poo teat every 2 years?

  • reply
    Katie Roberts
    11 February 2020

    Hi Mervyn,

    Thanks for your question about anaemia, blood tests and bowel screening.

    Different blood tests look for different things. Anaemia can be a symptom of bowel cancer, but it can also be caused by various other conditions, and not everyone with bowel cancer will be anaemic. The blood test before donating blood isn’t a good enough test for early signs of bowel cancer.

    The faecal immunochemical test (FIT) used during bowel screening specifically detects blood in your poo. This can be a sign of early stage bowel cancer in people who appear to have no symptoms.

    Thanks,

    Katie, Cancer Research UK

  • Frank Ball
    8 February 2020

    I had a cancer detected early by FOBt and had it removed 7 years ago. So for me this was a fantastic program and everyone needs to be encouraged to take part when the opportunity presents itself. This type of test is a life saver.

  • Susan Smith
    7 February 2020

    I had bowel cancer 2015. It was detected in a poo test and saved my life. It is important that people do the poo test when they are invited to

  • Helen carter
    6 February 2020

    Thank you for the information. I am sort to say that the poo screening tests are not at all accurate. My husband and I have always carried out these tests and until the last test we have both received normal results. The last screening my husband had came back with blood showing in the sample so he was requested to carry out. Repeat. This comeback normal . He had a rectal examination at our GP surgery no worries only piles or perhaps a polyp no need to worry. End of May 2019 he developed an accuse pain in left side. Went to GP thinking he had strained himself. Given blood tests endoscopy MR I scan CT scan and within two days diagnosed with inoperable bowel cancer. He died in under 4 months. He went from a lovely fit handsome 69 year old man to a shadow of himself. He died in front of my eyes Why was this cancer missed?

  • Antoinette Hasler
    6 February 2020

    Really informative article. Thank you.

  • Margaret Hook
    16 January 2020

    Thank you so much for this article about cancer and in particular bowel cancer. Actually knowing about these things is always good, trying to guess is not, so please keep reporting on cancer, I have had it three times so far, aged 89, very active so every grateful for any information you give. Incidentally I do not ‘live with cancer in my mind’ I rarely think about it at all and never think it might strike again. |Many thanks Margaret Hook

  • 4 December 2019

    Thanks for this. So useful

  • Tara Gipp
    4 December 2019

    Thanks for the great article. It would be interesting to see this expanded to pancreatic cancer,https://www.pancreaticcancer.org.uk/information-and-support/facts-about-pancreatic-cancer/signs-and-symptoms-of-pancreatic-cancer/

  • John Hunt
    28 November 2019

    I had a test a few weeks ago , it was one of those that’s advertised, £39 I think , it came back alright , should I have another couple to be sure , many thanks and keep up your fantastic work 👍 John Hunt .