Obesity increases the risk of colorectal cancer: Study

Research from the German Cancer Research Centre (DKFZ) shares that the association between colorectal cancer and obesity has likely been severely underestimated thus far. The cause is that many people accidentally lose weight before receiving a colon cancer diagnosis. When studies consider body weight at diagnosis, the true link between obesity and the risk of colorectal cancer is obscured. The new study also demonstrates that inadvertent weight reduction may be a precursor to colorectal cancer.
Herman Brenner, epidemiologist and prevention expert at the German Cancer Research Center, said, “However, these studies have so far not considered that many affected people lose weight in the years before their colorectal cancer diagnosis. This has led to the risk contribution of obesity being significantly underestimated in many trials.”
The nearly 12,000 study participants included in the current evaluation had provided information on their body weight at diagnosis. They reported their weight in the years preceding diagnosis (measured at 10-year intervals).
Based on body weight at the time of diagnosis, no indication of a relationship between body weight and colorectal cancer risk could be established. However, the picture was quite different when the researchers looked at the participants' earlier body weight: A strong correlation between being overweight and the probability of developing colorectal cancer was found, most pronounced 8 to 10 years before diagnosis.
Study participants who were highly overweight - referred to as obese- during this period were twice as likely as those of normal weight to develop colorectal cancer. "If we had only looked at weight at baseline, as has been done in many previous studies, we would have completely missed the link between obesity and increased risk of colorectal cancer," said Marko Mandic, the study's first author.