Large bowel cancer risk 1cm rise in waist circumference increases cancer risk

Speaking at the 23rd United European Gastroenterology Week (UEG Week 2015) in Barcelona, Spain, professor John Mathers, Professor of Human Nutrition from the Institute of Cellular Medicine at Newcastle University in the UK, revealed evidence linking excess body weight and risk of colorectal cancer (CRC). Mathers showed that an overall increase of 18% in relative risk of CRC per 5 unit increase in BMI.

“In addition, in men, there is now evidence that increasing waist circumference in middle age is associated with increased bowel cancer risk,” said Mathers. CRC risk was increased by nearly 60% in men who gained at least 10cm in waist circumference over ten years. “This increased cancer risk may be due to persistent inflammation in people with obesity.”

Patients with Lynch Syndrome (LS) have a higher than normal risk of CRC because of an inherited defect in one of the genes responsible for repairing DNA. Mathers presented new data showing that, in people with Lynch Syndrome, CRC risk increases with higher body weight and for those who are obese the risk of CRC is doubled. Quite surprisingly, the increase in CRC risk with higher body weight in people with Lynch Syndrome was about twice as great as that seen in the general population.

“There is now compelling evidence that improved lifestyle, particularly better dietary choices and being more physically active, can help to prevent obesity and this will lower bowel cancer risk,” he added.

In addition, for those people who are already too heavy, losing weight may reduce their CRC risk but this is an area which requires further study. In his studies with Lynch Syndrome patients, Mathers observed that aspirin lowered the excess CRC risk seen in patients with obesity, perhaps through its anti-inflammatory effects.

“This is a very intriguing finding which suggests that dietary and other anti-inflammatory agents might be beneficial in reducing CRC risk in people with obesity.”

“Bowel cancer is strongly associated with age, obesity and diet — and is driven by inflammation,” he added. “We can now give the public clear advice on the benefits of staying physically active, eating a healthy diet and avoiding weight gain to lower CRC risk as we get older.”