NEW YORK (Reuters) –, researchers in Germany report.
Their study “strongly supports suggestions that recent increases in prevalence of obesity in younger generations may be an important factor in the increases in incidence of early-onset CRC in many countries,” theyin Gastroenterology.
Dr. Hermann Brenner of the German Cancer Research Center, in Heidelberg, and colleagues also note that several countries have seen a rise in early-onset CRC, despite stable or declining rates in older adults.
They believe their study is among the first to evaluate associations between BMI at defined ages in early adulthood and the risk of early-onset CRC, defined for this study as onset before age 55.
The findings are based on an ongoing population-based case-control study of colon cancer in southwestern Germany, with more than 20 clinics providing CRC surgery to a population of about 2 million.
The 1,368 participants (747 CRC patients and 621 controls) were all under age 55, with a mean age of 48. To avoid confounding BMI data with potential weight loss in CRC patients shortly before diagnosis, weight and height information at ages 20 and 30 and roughly 10 years before diagnosis was used to calculate BMI.
The prevalence of overweight and obesity rose steadily from age 20 on among both cases and controls, but were higher among cases than among controls at all ages. Compared with participants with a BMI under 25 kg/m2, those with a BMI of at least 30 kg/m2 at age 20 and 30 years and approximately 10 years before diagnosis/interview had 2.56 (95% confidence interval, 1.20 to 5.44), 2.06 (95% CI, 1.25 to 3.40) and 1.88 (95% CI, 1.30 to 2.73) times higher risks of early-onset CRC.
A BMI between 25 and 30 was also significantly associated with higher risk, although the increase was less pronounced than for obesity.
Dr. Brenner told Reuters Health by email that it is unclear how to address the obesity epidemic in younger generations, “as this is currently subject to intensive research, with clear evidence being quite limited yet.”
“It seems, however,” he continued, “that reducing consumption of sugar-sweetened beverages from early childhood on may be a particularly important and promising approach.”
In an email to Reuters Health, Dr. Joshua Demb of Moores Cancer Center at the University of California, San Diego, praised the authors’ “thorough job examining early life measures of BMI in a large cohort of adults” and their “careful attention” to capturing height and weight data.
“Future research in this area should examine different early-in-life measures of obesity (that is, adiposity, visceral fat) and obesity-related constructs, such as physical activity or sedentary lifestyle factors, to better understand potential mechanisms in play,” he added.
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