Be thin to cut cancer, study says

Even those who are not overweight should slim down if they want to cut their risk of cancer, a major international study has claimed.

The World Cancer Research Fund carried out the largest ever inquiry into lifestyle and cancer, and issued several stark recommendations.

They include not gaining weight as an adult, avoiding sugary drinks and alcohol, and not eating bacon or ham.

Everyone must also aim to be as thin as possible without becoming underweight.

People with a Body Mass Index (BMI), a calculation which takes into account height and weight, of between 18.5 and 25, are deemed to be within a "healthy" weight range.

Cancer is not a fate, it is a matter of risk, and you can adjust those risks by how you behave. It is very important that people feel that they are in control of what they do Professor Martin Wiseman Report author

But the study says their risk increases as they head towards the 25 mark, and that everyone should try to be as close to the lower end as possible.

There is no new research involved in this document: the panel examined 7,000 existing studies over five years.

The result, they say, is the most comprehensive investigation ever into the risks of certain lifestyle choices.

RECOMMENDATIONS INCLUDE: Limit red meat Limit alcohol Avoid bacon, ham, and other processed meats No sugary drinks No weight gain after 21 Exercise every day Breastfeed children Do not take dietary supplements to cut cancer

They see body fat as a key factor in the development of cancer, estimating its significance to be much higher than previously thought.

The report's authors say they have produced a list of recommendations, not "commandments".

"But if people are interested in reducing their cancer risk, then following the recommendations is the way to do it," said Professor Martin Wiseman.

"Cancer is not a fate, it is a matter of risk, and you can adjust those risks by how you behave. It is very important that people feel that they are in control of what they do."

Making cuts

However, two-thirds of cancer cases are not thought to be related to lifestyle, and there is little people can do to prevent the disease in these circumstances.

Nevertheless, more than three million of the 10 million cases of cancer which are diagnosed across the world each year could be prevented if the recommendations were followed, Professor Wiseman indicated.

The main message I would have is not to worry about it, to enjoy life, if you like a glass of wine have it, and a small amount of meat is not going to harm you Karol Sikora Cancer specialist

In the UK alone, there are 200,000 new cases of cancer each year.

Cancers of the colon and breast are some of the most common forms of the disease, and the report says the evidence is "convincing" that body fat plays a key role in the development of these tumours.

The report also links the kind of food consumed to cancers, especially colorectal ones.

In particular, researchers say people should stop eating processed meats, such as ham, bacon and salami, and limit the consumption of red meat to 500g a week - although this still means you could eat, for instance, five hamburgers each week.

From a cancer perspective, all alcohol should be avoided, although researchers accepted drinking small amounts could have protective benefits for other diseases.

The recommendation is therefore no more than two drinks a day for a man, and no more than one for a woman, slightly less than current UK government guidelines.

Sugary drinks meanwhile should be avoided, as these make you fat, and fruit juice consumption should also be reduced.

The report is also the first to urge breastfeeding as a means to protect against cancer, arguing that it may reduce breast cancer in the mother and prevent obesity in the child - although this has not been proven.

Commenting ahead of the report's release, cancer specialist Professor Karol Sikora said: "There's absolutely nothing magic about 10 bullet points to prevent cancer.

"The main message I would have is not to worry about it, to enjoy life, if you like a glass of wine have it, and a small amount of meat is not going to harm you."

Chilli compound fires painkiller

A chemical from chilli peppers may be able to kill pain without affecting touch or movement.

This might in theory mean a woman in labour could have an epidural without losing the ability to move her legs, or the sensation of her baby being born.

Conventional local anaesthetics affect all nerve cells.

But the researchers Harvard team, writing in Nature, said that with capsaicin, the chilli chemical, they can target just pain receptors.

However, a UK expert said it might be difficult to inject it safely.

The Holy Grail in pain science is to eliminate pathologic pain without impairing thinking, alertness, coordination or other vital functions of the nervous system Dr Story Landis National Institute of Neurological Disorders and Stroke

Numbness is actually a side-effect of the pain-killing properties of local anaesthetics - caused when the drug blocks signals not only from the nerve endings which cause pain, but other nerve endings which simply detect the sensation of touch.

And when anaesthetic "blocks", are injected into the spine, they can interfere with other nerves, causing temporary paralysis - such as that felt in the lower limbs after an epidural injection.

Cell door

The Harvard team used a molecule - QX-314 - which interferes with nerve signals in the same way as any other conventional anaesthetic, but which is too big to get into any nerve cell on its own.

Capsaicin, which is the substance that makes chilli peppers taste "hot", has an unique property - it can open a channel in the cell wall of nerve cells big enough for QX-314 to get in.

However, it can only do this in the cell walls of pain receptor neurons, meaning that these are the only nerve cells affected by the anaesthetic.

The technique has not yet been tried on humans, and it is hard to see how capsaicin could be used in this situation Dr Joan Hester British Pain Society

In rats, an injection of QX-314 and capsaicin killed pain, and caused no other effects. And when injected near the nerve controlling the hind leg, there was no paralysis.

The researchers said that this had the potential to "profoundly change pain treatment" before and during the millions of operations carried out under local anaesthetic every year.

Dr Story Landis, the director of the National Institute of Neurological Disorders and Stroke in the US, said that patients in chronic pain might also benefit.

"The Holy Grail in pain science is to eliminate pathologic pain without impairing thinking, alertness, coordination or other vital functions of the nervous system.

"It holds the promise of major future breakthroughs for the millions of people who suffer with disabling pain."

Burning feeling

Dr Joan Hester, the president of the British Pain Society, said that while capsaicin had been used for many years to reduce skin sensitivity linked to chronic pain, it caused an unpleasant burning sensation that was too much for some patients.

This might be even more of a problem if the chemical was injected below the skin, she said.

"The technique has not yet been tried on humans, and it is hard to see how capsaicin could be used in this situation."

However, she said that the study broke new ground: "Selective block of pain nerve fibres without numbness or motor block would be of great benefit in local anaesthesia by injection, for example in epidural anaesthesia"