Obesity raises risk of various types of cancers

12 October, 2007

The growing ‘epidemic’ of obesity is leading to an increase in the risk of developing a number of cancers, including cancers of the breast, womb and prostate.

A study conducted by Cancer Research UK, a charity organization of the United Kingdom, has found that the number of men and women under the age of 45 who are morbidly obese has doubled in the past decade. This increase in obesity means that more people are at risk of developing various types of cancer.

Professor Jane Wardle, director of Cancer Research UK’s health behavior unit, said slim people stayed roughly the same size over the 10 years, but the weight of heavier people dramatically increased.

A rather sedentary lifestyle – like sitting at a computer for long hours – takeaway meals, and snacking were all contributory factors.

Two cancers that claimed most lives in the United Kingdom – breast cancer and colorectal cancer – were among those that had been linked with obesity, Prof Jane Wardle said, adding: “We are seeing evidence of a rise in the number of cancers that can be caused by obesity just when we are seeing a reduction in those caused by smoking.”

Being overweight or obese upsets the metabolic environment and accelerates cell damage as well as the fat-secreting hormones that could trigger tumors.

Obese people are at a greater risk of getting cancers of the womb, gall bladder and kidney and obesity could also increase the risk of prostate and pancreatic cancers. The biological link between obesity and cancer is complicated, but maintaining a healthy body weight will reduce cancer risk, Prof Jane Wardle said.

According to Dr Lesley Walker, of Cancer Research UK, this research adds to the evidence that the United Kingdom is in the grip of an obesity epidemic. He explains: “We know that high body weight increases the risk of a number of cancers and it is important we get this message to as many people as possible. A healthy diet with plenty of fibre, fruit, and vegetables as well as regular exercise can help people lose weight and reduce their risk of cancer.”

Growth of obesity among Britons was measured by taking the weight and waist measurements of 12,000 people during 1993-94 and contrasting them with a similar group 10 years later.

The number of men grouped as obese went up from 13.4% to 22.7%, while the level of obese women rose from 15.8% to 22.4%. Men’s waist circumference expanded by 1.37 inches (3.48 centimetres) and women’s by 1.71 inches (4.35 centimetres).

The study by Cancer Research UK also looked at a person’s body mass index (BMI), which is calculated by dividing weight in kilograms by the square of a person’s height in metres. To be considered morbidly obese, a person must have a BMI of 35 or more.

Between 1994 and 2004, the number of British women with a BMI of more than 40 doubled.

Research has also shown that 12,000 cases of cancer could be prevented each year if a person’s BMI did not exceed 25 – which is classed as overweight.