Abdominal Fat May Raise Colon Cancer Risk

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Updated: 10:10 PM EDT

Abdominal Fat May Raise Colon Cancer Risk

By Amy Norton, Reuters

NEW YORK (July 5) - Adults who carry much of their fat around the

middle may be at increased risk of colon cancer, a large European

study suggests.

Researchers found that among nearly 370,000 adults from nine European

countries, men and women with large waistlines were more likely to

develop colon cancer than those who were trimmer around the middle.

Waist size and waist-to-hip ratio, which are both indicators of

abdominal obesity, appeared more important in colon cancer risk than

does overall weight. In fact, the study found that body mass index

(BMI) -- a measure of weight in relation to height -- was unrelated to

colon cancer risk among the women.

The findings, reported in Wednesday's issue of the Journal of the

National Cancer Institute, suggest that abdominal fat holds a

particular influence over colon cancer risk.

People with large waistlines often have a high amount of fat around

the abdominal organs, and this type of fat is more " metabolically

active, " explained Dr. Tobias Pischon, a researcher at the German

Institute of Human Nutrition in Potsdam-Rehbruecke and the lead author

of the study.

It's possible, he told Reuters Health, that this visceral fat

increases colon cancer risk by raising levels of certain hormones that

affect cell growth, including the growth of cancer cells. For example,

the researcher noted, people with type 2 diabetes have a higher rate

of colon cancer -- supporting a potential role for the hormones

insulin and insulin-like growth factor 1 in promoting tumor cell growth.

Whatever the reason, the new findings point to the importance of

preventing abdominal obesity in particular, according to Pischon.

The findings come from a large ongoing study of nutrition and cancer

risk among European adults. The researchers included 368,277 men and

women who had their weight and body measurements taken and who

completed questionnaires on diet, exercise and other lifestyle factors

at the start of the study.

Over the next six years, the researchers found that adults with larger

midlines were more likely to develop colon cancer. Compared with the

slimmest men, those with the largest waistlines were 39 percent more

likely to be diagnosed with the cancer; women with the most fat around

the middle had a 48-percent higher risk of the disease than those with

the smallest waistlines.

BMI was linked to colon cancer risk among men only.

Previous studies have found the same sex difference when it comes to

BMI and colon cancer risk, according to Pischon's team. One reason,

they note, may be the differences in body fat distribution between men

and women.

When a man has a high BMI, it's typically because of fat around the

middle. Women, on the other hand, often carry much of their fat around

the hips and thighs.

So waist size may be a more accurate predictor of colon cancer risk

than overall BMI, particularly for women, according to Pischon.

" Our study shows that it's more important to keep an eye on the waist

circumference, especially in women, " he said.

07/05/06 12:27 ET