Weight Control and Exercise Could Prevent 20% of Colon Cancer

September 16, 2010 — Around 20% of colon cancer in European countries could be prevented if the whole population managed to reach optimum levels of weight and physical activity, suggest new projections.
The data are reported in the September issue of the European Journal of Cancer, which is dedicated to cancer prevention.
An increasing proportion of the European population now has a body mass index (BMI) higher than 25 kg/m², and few Europeans are engaging in the amounts of physical activity recommended by current guidelines (at least 30 minutes of moderate-intensity activity 5 or more days a week), the researcher note.
The researchers set out to predict what would happen if the European population managed to maintain a mean BMI of 21 kg/m² and if all countries had a level of physical activity similar to that seen in the Netherlands, where both cycling and walking are popular.
They used the PREVENT statistical modeling method, which was developed at Erasmus University in the Netherlands and is frequently used in the European Union's EUROCADET project.
"We know that large numbers of colon cancer cases could be avoided by reducing exposure to risk factors," said senior author Andrew Renehan, PhD, FRCS, FDS, from the School of Medicine, University of Manchester, United Kingdom. And 2 of the most easily controllable risk factors are physical inactivity and excess weight, he added.
"The predictive modeling is beginning to tease out the independent relevance of each of these factors in the prevention of colon cancer," he said in a statement.
"Preventing weight gain and encouraging weight reduction seem to be most beneficial in men, but for women a strategy with a greater emphasis on increasing physical activity would be more effective," he explained.
Colon Cancer Increasing
Colon cancer rates are increasing in Europe; they have been on the rise since 1975. It is the second most common cancer in Europe and the second most common cause of cancer death, the researchers note.
In a previous study, Dr. Renehan and colleagues attributed the increasing rates of all cancers to increasing obesity in European countries. They estimated that in 2008, new cancers attributed to excess body weight affected 3.2% of women and 8.6% of men; this was an increase from the estimates for 2002, which projected that excess weight was related to new cancers in 2.5% of men and 4.1% of women.
Those data were presented at the 2009 meeting of the European Cancer Organization, and reported by Medscape Medical News at the time.
"People in Europe are gaining weight," Dr. Renehan said at the time, "and it is projected to keep rising."
In the new study, the researchers used the computer model to look at what would happen if Europeans continued to grow fatter, using a hypothetical scenario in which obesity levels increased at the same rate as they have in the United States. They predicted that this would lead to an increase in the number of new colon cancer cases of between 0.7% and 3.8%, depending on the European country.
Then they hypothesized a scenario in which Europeans managed to control their weight and managed to achieve an optimum BMI of 21 kg/m². They calculated that by the year 2040, this weight-control strategy would prevent between 2% and 18% of colon cancer cases across the countries they studied. The benefits were much higher for males (13.5% to 18%) than for females (2.3% to 4.6%), and most benefit would be seen in British males (in whom 18% of new colon cancer cases could be prevented).
This "underlines the importance of stopping and reversing the ongoing increase in overweight and obesity prevalence," the authors note.
When the team considered physical activity, they found that the Netherlands had the highest rates, which they attributed to a high frequency of bike use, often as a means of transportation. They also found high levels of walking.
Using the Netherlands as the ideal, the researchers predicted what would happen if other countries adopted the same amount of physical activity. They found that overall, 17.5% of new colon cancer cases could be prevented by 2040, with the most benefit in Spanish females (in whom 21% of new colon cancer cases could be prevented).
"We can safely say that increasing physical activity across Europe to the level already achieved in the Netherlands, where everyone cycles, would be of substantial benefit," said coauthor Jan-Willem Coebergh, MD, PhD, from Erasmus University.
"In summary, the changes in physical activity and/or mean levels of overweight in the selected European populations would result in quite substantial effects on future colon cancer rates," the authors conclude.
The researchers have disclosed no relevant financial relationships.
Eur J Cancer. 2010;46:2605-2616.