Mouse study: Bowel cancer 'could be fuelled by E coli stomach bug'
Or is it that mice with cancer are more likely to get e-coli through weakened resistance?
One of Britain’s most common cancers could be fuelled by the E coli stomach bug, scientists believe.
The breakthrough raises the prospect of a vaccine against bowel cancer, which claims 16,000 lives a year and is the second most common form of the disease in women after breast cancer and the third most diagnosed in men.
The elderly, who are most at risk of the bowel cancer, could also be screened for the ‘sticky’ strain of E coli that makes a DNA-damaging poison.
Although the idea that a bug is involved in cancer might seem strange, it is not unheard of, with a virus being to blame for most cases of cervical cancer and a bacterium strongly linked to stomach cancer.
Now, tests on mice and people, carried out in the UK and US, have pointed to E coli being a strong suspect in bowel cancer.
The concern surrounds a version that sticks well to the inside of the lower bowel, or colon. It also contains genes that make a poison which causes the type of damage to DNA usually seen in cancer.
Although we usually think of E coli as causing food poisoning, these strains had been thought to live in the bowel without causing any problems.
However, tests show them to be much more common in bowel cancer patients than in healthy people.
Two-thirds of the 21 samples taken from bowel cancer patients contained the bug, compared to just one in five of those taken from healthy people, the journal Science reports.
Experiments also showed that mice inoculated with the bug are at very high odds of developing bowel cancer – as long as the E coli carries the poison-making ‘pks’ genes.
Liverpool University’s Dr Barry Campbell, a co-author of the study, said: ‘The research suggests that Ecoli has a much wider involvement in the development of colon cancer than previously thought.
‘It is important to build on these findings to understand why this type of bacteria, containing the pks genes, is present in some people and not in others.’
Professor Jonathan Rhodes said: ‘The bottom line message is that there seems to be a strong association between a type of E coli and the development of colon cancer.
‘And given that this type of E coli is specifically able to damage DNA and inflict the sort of damage you get in a cancer, it is very likely it has a causative role, at least in some patients.’
The scientists, who collaborated with scientists from the University of North Carolina, aren’t sure why some people who have the bug go onto develop cancer and others don’t.
But factors such as genes and diet are probably important.
Professor Rhodes said: ‘The literature on colon cancer taken as a whole suggests that having the right genes, taking exercise, possibly taking an aspirin a day, limiting red meat and eating plenty of leafy green vegetables all have a protective effect.’
If the link is confirmed, it could lead to tests for the rogue form of E coli being included in bowel cancer screening for the elderly.
In the long-term, a vaccine that stops the bug from taking root is also possible, added the professor.
There is a precedent for this – the HPV vaccine which is given to teenage girls wards off infection by the human papilloma virus - the bug behind the majority of cases of cervical cancer.
Henry Scowcroft, of Cancer Research UK, said: ‘This is an intriguing study in mice suggesting that the bacteria in our gut may play a role in the development of bowel cancer.
‘This would make sense, as we know that being infected with bacteria called H pylori can increase the chances of developing stomach cancer.
‘But since this study only involved mice and is still at an early stage, it’s not yet clear whether E coli is actually linked to bowel cancer in humans at all, let alone whether this knowledge could be used to help improve things for patients or people at risk.’
How your blood group can affect your heart disease risk: Britons with 'O' type 'benefit from natural protection'
The Japanese are fanatical about blood type. Maybe they are onto something! The effects below are however too small to be given much credence
A person’s blood group helps determine their risk of heart disease, a study has found. Researchers claim almost half of Britons with blood group O, the most common blood type, benefit from some natural protection against the illness.
However, they said people from groups A and B are more at risk, while people from AB, the rarest blood group, are the most vulnerable.
The findings, published in the journal Arteriosclerosis, Thrombosis and Vascular Biology, are based on an analysis of two large US health and lifestyle studies.
The Harvard University researchers concluded people with blood group AB were 23 per cent more likely to suffer from heart disease. Group B blood increased the risk by 11 per cent, and type A by 5 per cent.
Lead researcher Professor Lu Qi, from the Harvard School of Public Health in Boston, said ‘While people cannot change their blood type, our findings may help physicians better understand who is at risk for developing heart disease.
‘It’s good to know your blood type the same way you should know your cholesterol or blood pressure numbers. 'If you know you’re at higher risk, you can reduce the risk by adopting a healthier lifestyle, such as eating right, exercising and not smoking.’
The study compared blood groups and heart disease incidence but did not analyse the complex biological mechanisms involved.
There is evidence that type A blood is associated with higher levels of ‘bad’ type of cholesterol, low density lipoprotein (LDL), which is more likely to fur up the arteries.
AB blood is linked to inflammation, which also plays an important role in artery damage.
People with type O blood may benefit from a substance that is thought to assist blood flow and reduce clotting.
The researchers pointed out the study group was mostly white Caucasian and it is not clear whether the same findings applied to other ethnic groups.
Prof Qi said ‘It would be interesting to study whether people with different blood types respond differently to lifestyle intervention, such as diet.’
Scientists from Pennsylvania University last year found the same gene that causes people to be blood group ‘O’ gives them some protection against heart attack.
But experts warn that while blood type O may offer some protection from heart trouble, blood type alone will not compensate for other factors that are linked to cardiovascular disease.
Other research found blood group O patients may be at greater risk for bleeding and blood transfusions after heart surgery. Patients with AB blood type are 20 per cent less likely to die after heart bypass surgery than those with A, B or O blood types, said Duke University Medical Center researchers.
Doireann Maddock, Senior Cardiac Nurse at the British Heart Foundation, said ‘While these findings are certainly interesting we’ll need more research to draw any firm conclusions about blood type and its role in heart disease risk.
‘Nobody can influence what type of blood they are born with but a healthy lifestyle is something everybody can have an influence over. Eating healthily, getting active and stopping smoking are the types of things you should be worrying about, not your blood type.’