Adolescents and young adult men who are obese or have elevated inflammatory blood markers appear to be at increased risk of developing colorectal cancer later in life, according to study findings presented at the American Association for Cancer Research International Conference on Frontiers in Cancer Prevention Research.
During an average 35 years of follow-up, those who were obese—as measured by body mass index as adolescents—were 2.37 times more likely to develop colorectal cancer than their counterparts with a normal BMI. Those with high levels of inflammation had a 63 percent higher risk than did those with low levels.
Researchers at Harvard School of Public Health analyzed data collected from 239,464 Swedish men conscripted into military service between the ages of 16 and 20 from 1969 to 1976. During their entrance physical, erythrocyte sedimentation rate was measured, as was their height and weight. By linking the conscription registry with Sweden's national cancer register, the team next looked at colorectal cancer diagnoses through 2009, and 885 cases were recorded.
“Our results suggest that early-life body mass index and inflammation may independently play a role in the development of cancer later in life,” said Elizabeth Kantor, PhD, a postdoctoral research fellow in the Department of Epidemiology.
However, further research is needed to better understand these relationships, she noted, pointing to limitations in the data. The registries used do not contain information on all variables, such as adolescent diet.
“Obesity was relatively uncommon among adolescents in Sweden at the time the cohort of men enlisted, and it is possible that ‘obesity’ in this study represents something different from what is represented by ‘obesity’ in populations in which this exposure is more ubiquitous,” she added.
The association needs to be investigated in large cohorts from different populations, and further research is needed to separately examine body mass index and inflammation from associated exposures and from exposures at other points as they age, Kantor said.
Asked his opinion, Clifford Hudis, MD, ASCO's Immediate Past President and coauthor of the society's new position statement on obesity (see page 8) said the study is consistent with the overall theme that has been observed elsewhere, that being overweight or obese represents a life-long health risk: “This is why we need to better understand this risk so that we can constructively address it,” he said.