Men and women with a large waist circumference and a large waist-to-hip ratio (WHR) have an increased risk of developing colon cancer. In contrast, only in men is a high body mass index (BMI) clearly associated with a higher colon cancer risk.
However, there is no relation between the body measures of the investigation and rectal cancer risk. These results from the European-wide EPIC study (European Prospective Investigation into Cancer and Nutrition) were published on July 5th by Tobias Pischon of the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE) and his colleagues in the Journal of the National Cancer Institute.
“Our results support the hypothesis that abdominal body fat is especially important for development of colon cancer. This agrees with our observation that BMI is rather inappropriate for predicting colon cancer in women because the relation between BMI and waist circumference is not as close as in men. This is probably because men gain weight primarily by increasing abdominal body fat, whereas in women, body fat normally also accumulates in other parts of the body”, says Heiner Boeing, head of EPIC Potsdam. “Why increased abdominal fat raises the risk of colon cancer is currently unknown. The insulin resistance associated with abdominal obesity and the resulting increase in circulating insulin levels may possibly play a role. Other potential mediators are leptin and adiponectin. We are currently examining within EPIC these and other biomarkers for their possible association with colorectal cancer.”
In addition to DIfE, the Deutsche Krebsforschungszentrum in Heidelberg is the second German study center involved in EPIC.
The researchers examined in 368,277 EPIC participants the associations between various body measures and the risk of colon and rectal cancer. The analysis is based on a circa 6-year follow-up during which 984 participants developed colon cancer and 586 rectal cancer.
The epidemiologists came to the following conclusions: Women with a WHR over 0.85 had a 52 percent higher risk of colon cancer than those with a WHR under 0.73. Similar values were observed in men, whose colon cancer risk increased by 51 percent from the group (quintile) with the lowest WHR (<0.89) to the group with the highest WHR (=0.99).
Height was also rather strongly associated with cancer risk in both sexes. Women taller than 167.5 cm had a 79 percent higher chance of developing colon cancer than short women (<156.0 cm). In men, between the shortest (<168 cm) and the tallest ones (=180.5 cm), this risk increased by 40 percent.
In contrast, sex-specific differences were observed with BMI. Men with a BMI over 29.4 had a 55 percent higher risk of colon cancer than slim men with a BMI under 23.6. In women, the risk increased by only 6 percent at the most between the corresponding groups.
The Body Mass Index (BMI) is calculated by dividing the body weight [kg] by the square of the body height [m2].
A greater height (tallness) is associated with a higher colon cancer risk. One possible reason for this is the higher number of cells per se: The higher the number of cells present, the higher the probability of cell mutations. In addition, taller individuals probably have a relatively high exposure to growth-regulating hormones (growth hormone, insulin-like growth factors and insulin), which in turn are associated with cancer development.
Leptin is an appetite inhibiting hormone secreted by fat cells. It is primarily involved in the regulation of body fat metabolism and stimulates growth of colon epithelial cells.
Adiponectin is a hormone secreted by fat cells. Low adiponectin levels are a risk factor for the later development of type 2 diabetes. Adiponectin also has antiangiogenic and antitumor activities.