New research suggests there is an increased risk of large bowel cancer for each 1 centimeter rise in waist circumference.

British researchers found an overall increase of 18 percent in relative risk of colorectal cancer per 5 unit increase in body mass index.

"In addition, in men, there is now evidence that increasing waist circumference in middle age is associated with increased bowel cancer risk," researcher John Mathers, professor of Human Nutrition from the Institute of Cellular Medicine at Newcastle University in the UK , said in a statement. "This increased cancer risk may be due to persistent inflammation in people with obesity."

Colorectal cancer risk was increased by nearly 60 percent in men who gained at least 10 cm in waist circumference over 10 years.

Based on his findings, Mathers concluded that colorectal cancer risk increases with higher body weight and for those who are obese the risk of colorectal cancer is doubled. Quite surprisingly, the increase in colorectal cancer 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," Mathers said.

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, Prof. Mathers observed that aspirin lowered the excess CRC risk seen in patients with obesity, perhaps through its anti-inflammatory effects.

Mathers said this is a very intriguing finding which suggests that dietary and other anti-inflammatory agents might be beneficial in reducing the risk of developing colorectal cancer in people with obesity.

"Bowel cancer is strongly associated with age, obesity and diet -- and is driven by inflammation," Mathers said. "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 colorectal cancer risk as we get older."

The findings were presented at the 23rd United European Gastroenterology Week in Spain.