Overweight boys have a higher risk of developing colon cancer in adulthood, but if they lose the extra pounds by young adulthood, that higher risk goes away, a Danish study found.
While prior studies have shown that overweight children are more likely than those of normal weight to develop colon cancer as adults, no study had looked at the impact of changes in body mass index from childhood to adulthood.
To see if overweight boys who had slimmed down as young adults were still at increased risk for colon cancer, Dr. Britt Wang Jensen, associate professor Jennifer Baker and their colleagues examined the health records of more than 61,000 Danish schoolboys born between 1939 and 1959.
The researchers collected participants’ weight, height and body-mass index (BMI) at age 7 and in young adulthood, between ages 17 to 26. The participants were then linked to the Danish Cancer Register, and followed from the age of 40 to identify colon cancer cases.
After a median follow-up of 25 years, more than 700 men had developed colon cancer. The data showed that boys who were overweight throughout their childhood and early adulthood had twice the risk of colon cancer compared to those who had a normal weight. But if overweight boys achieved a normal weight by adulthood, they were no longer at particular risk.
“However, overweight boys who remain overweight as young men have an increased risk of adult colon cancer. These results highlight the importance of weight management in childhood,” the researchers said in a press release. “Our next steps are to expand our focus and examine other forms of cancer along with other non-communicable diseases to create a full picture of how a man’s weight development across his life — even from birth — is associated with his risk of disease.”