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Bowel cancer – detection, prevention and cure

To mark Bowel Cancer Awareness Month Justin Davies, Clinical Director for BowelHealth UK, talks about new developments in screening techniques, risk factors and why all those who are invited should take the test.

Check4cancer small size 17Justin Davies is a Consultant Colorectal Surgeon at Addenbrooke’s Hospital, Cambridge, where he is also Clinical Director of General Surgery. He has a strong research pedigree in bowel cancer screening, and is the recipient of several prestigious research prizes, including the Patey Prize and John of Arderne Medal, lecturing on this topic nationally and internationally. He is a Member of Council of The Royal Society of Medicine Section of Coloproctology and is the current Chair of the Education and Training Committee of the Association of Coloproctology of Great Britain and Ireland. Justin joined BowelHealth UK in July 2013 as Clinical Director.

First of all, can you describe how you came to be involved with bowel cancer?
I am a Consultant Colorectal Surgeon at Addenbrooke’s, Cambridge, and Clinical Director for Digestive Diseases at the hospital. I'm also a member of the Council of the Association of Coloproctology of Great Britain and Ireland, and have a research pedigree in novel and non-invasive methods of screening for bowel cancer. That was what initiated my interest in bowel cancer, and I now regularly operate on patients who have bowel cancer.

It’s Bowel Cancer Awareness Month this April, but why is awareness important, and what should we be aware of?
There are some confounding issues with bowel cancer. The first is that it can be present with no symptoms, and it's very difficult to be aware when you don't have any symptoms. But what people therefore need to be aware of is that there is a national bowel cancer screening programme that will invite them to be involved, which can detect bowel cancer or its non-malignant precursor, bowel polyps. So there's an awareness of that screening programme that people need, so they can at least have the chance to engage in the process and overcome the problem of the potentially asymptomatic nature of the disease. Then there is also an awareness of what symptoms can occur when it is a symptomatic disease – all the things we classically ask them to look for, in terms of bleeding from the bottom, changes in bowel habit, unexplained weight loss and so on. So, it is a double-pronged issue.

Is part of that awareness to do with understanding the impact of say, age or lifestyle on ones individual risk?
Yes, there is also an element of that. A significant family history of bowel cancer can mean an increased risk, as can age – that is, the older we get, the more we are at risk. There are also some factors that predispose people to bowel cancer, including ulcerative colitis or Crohn's Disease – so-called inflammatory bowel diseases. If people have a personal risk of those, they can make cancer more likely. Then there are lifestyle factors, such as being overweight, having reduced exercise, and alcohol intake.

Processed meats were in the news last year when WHO classified them as carcinogens. Should we be cutting these products out?
I don't think the evidence is strong enough to say that people should never eat them. I think on balance that it's a matter of being aware of the benefits of a healthy diet – one that is high in fresh fruit and vegetables and fibre, and lower in processed and red meat.

What does the national bowel cancer screening programme consist of?
When it started, it was just a Faecal Occult Blood Test (FOBT) programme, between the ages of 60 and 69, with that age band later being extended to 74. We know that the Faecal Occult Blood Test is not the most sensitive test either for bowel cancer or bowel polyps, but in terms of a national bowel cancer screening programme it is safe, it is economically viable and there is randomised control trial evidence both from Europe and the US to support its use, and we do see a reduction in the incidence of bowel cancer in populations screened using FOBT. So, we know it is effective. But now, a national programme of flexible sigmoidoscopy is being rolled out, with people being offered a one-off flexible sigmoidoscopy from the age of 55. The benefit of the flexible sigmoidoscopy is that it can immediately find polyps and then remove them. That is the whole aim of bowel cancer screening, really; detecting bowel cancer at its earliest stage, and more importantly detecting the early precursors of bowel cancer – bowel polyps – which can be removed by the flexible sigmoidoscopy camera to prevent bowel cancer forming in the future. Bowel cancer forms from changes in these benign bowel polyps. The issues, however, are really about uptake – only 58% of the people offered a test actually go through with it. That 58% compares to 72% uptake for breast cancer screening and 79% for cervical cancer.

What numbers are we talking about here?
The latest figures publically available show that between July 2006 and December 2010, 7,065 cancers were detected through the programme and over 40,000 patients had undergone polyp removal. Obviously, there could be many more if uptake were increased. In 2013, there were 41,112 new cases of bowel cancer in the UK: 22,957 (56%) in men and 18,155 (44%) in women. The crude incidence rate shows that there are 73 new bowel cancer cases for every 100,000 males in the UK and 56 for every 100,000 females. The key point is that when caught early, over 90% of cases can be treated successfully, so if bowel cancer screenings had the same level of uptake as cervical cancer, that would mean literally thousands of lives being saved.

I understand that Check4Cancer uses a more accurate testing method – is this likely to become standard for the national screening programme?
Check4Cancer uses an immunochemical FOBT, which is accurately detecting human blood, as opposed to the standard FOBT used currently in the national bowel cancer screening programme in England, which can detect non-human blood, and so can be influenced by dietary factors, such as eating red meat. So, the immunochemical FOBT is more accurate. It is already used as part of the national bowel cancer screening programme in Scotland, and it is almost inevitable that this test will be introduced in the programme in England.

What developments would you like to see in terms of testing?
We don't yet know which bowel polyps are likely to turn cancerous and which aren't, so the Holy Grail of bowel cancer screening would be an accurate way of knowing which were going to transform into cancer so we could leave the harmless ones behind. Also, knowing which people had the genetic changes that meant they were definitely going to get it, or definitely not. In terms of screening, where we would like to get to is even less invasive tests. We could look at more accurate stool-based tests – and there is in fact a more sensitive stool-based test that finds genetic mutations, which the cells have shed into the stool, but at the moment that is very expensive. It would also be more acceptable to subjects if there were a blood test rather than a stool test. Various tests have been tried but none are yet quite fit for purpose. There is some interesting work going on with regard to breath analysis, however – being able to detect bowel cancer by looking for certain volatile chemicals that occur in breath, and which can indicate the presence of cancer.

So, what are the key messages?
The key messages are knowing about screening and taking advantage of it. It's obviously important that people seek advice quickly if they have symptoms, but also that they take part in screening programmes that are available to them, because in the asymptomatic group, if we detect benign polyps, then we can actually prevent them from getting cancer in the first place.

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