Obesity closely linked to cancer

Nov 1 2007 Western Mail

BODY fat and obesity are far more closely linked to cancer than is generally realised, according to the result of a landmark study released yesterday.

Scientists have hailed the discovery of a direct link between weight gain and the risk of cancer as a milestone in the fight against the disease.

The largest-ever inquiry into the link between lifestyle and cancer urges adults to slim down and change their eating habits.

Key recommendations include:

Stop eating processed meat, including ham, bacon, pastrami and frankfurters

Cut down on alcohol

Avoid sugary drinks

Breastfeed children

Exercise daily

The report by the World Cancer Research Fund said there was “convincing” evidence that excess body fat can cause six different types of common cancers, including those affecting the breast, bowel and pancreas.

To guard against cancer, everyone should be at the lower end of the healthy weight range, the scientists warned.

The report will add urgency to efforts to combat the obesity epidemic in Wales.

This year’s Health Statistics Wales report found 60% of men and half of women reported being overweight or obese.

Major lifestyle changes will be required as a result if people are to act on the findings. The link between processed meat – including ham and bacon – is so compelling the report recommends individuals avoid it completely.

The report is based on an in-depth analysis of 7,000 cancer studies from around the world dating back to the 1960s.

A specific strong link is said to exist between fat around the abdomen and bowel cancer.

There is also a “probable” connection between body fat and gall bladder cancer, and abdominal fat and pancreatic, post-menopausal breast, and endometrial cancer, the evidence suggests.

Professor Sir Michael Marmot, who chaired the expert panel, said, “We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood. This might sound difficult, but this is what the science is telling us more clearly than ever before.

“The fact is that putting on weight can increase your cancer risk, even if you are still within the healthy range. So the best advice for cancer prevention is to avoid weight gain, and if you are already overweight then you should aim to lose weight.”

Simon Morgan Jones, health education officer with Cardiff-based cancer charity Tenovus, said, “Increasingly, we are becoming aware of the need for [a healthy] diet and regular exercise.”

He said people should not be frightened by the research and could enjoy alcohol and red meat in moderation.

David Bailey, chairman of the GPs’ committee in Wales, welcomed the report but did not think funding should be diverted from medical research to education efforts designed to urge weight loss. Obesity levels had soared, he argued, despite anti-fat campaigns.

He said, “I’m not convinced educating people makes people thinner.”

Dr Bailey favoured better labelling of food and creating new opportunities for exercise. A healthy diet and regular exercise would also help combat diabetes, heart disease and depression, he added.

High-calcium diets – which tend to include dairy products – were found to be a probable cause of prostate cancer. There was limited evidence suggesting that high consumption of milk and dairy foods can trigger this disease.

Mothers’ milk, in contrast, was convincingly found to protect women against breast cancer. It also “probably” protected the breast-fed child against obesity later in life, and thereby cancer.

Mothers were advised to breastfeed exclusively for six months and to continue with complementary breastfeeding after that time.

Alcoholic drinks were strongly linked to mouth, oesophagus and breast cancers. But the panel said although there were no “safe” alcohol limits for cancer, this had to be balanced against the protective effect modest alcohol consumption was said to have against heart disease.

An Assembly Government spokesman said, “Cancer is linked to a range of risk factors, of which obesity is one.

“Tackling cancer is one of our top priorities and by promoting better health through health eating, physical activity and the introduction of the smoking ban, we hope to reduce its incidence in the long term. Wales has long recognised the potential impact of obesity and has been working hard to reduce this.

“We place great importance on the need to improve public health in general to reduce pressure on the NHS in the long-term and improve people’s health and well-being.”

Measuring the ideal
Clinical obesity is defined as a Body Mass Index (BMI) of 30 or above.

The “ideal” BMI range for the population has been estimated at between 21 and 22.

BMI is calculated by dividing a person’s weight in kilograms by height in metres squared. A figure of 18.5 to 24.9 is considered “normal” and 25 to 29.9 “overweight”.

Being obese is known to be linked to heart disease and type-two diabetes.

Waistline circumference is another key health indicator. Men with an abdominal girth of 37 inches and over and women with 31.5 inches are said to be at risk.