SAN DIEGO. Being overweight in childhood appears to increase the risk of obesity-related cancers in men later in life, even if they lose the extra pounds as adults, a researcher reported here.
During more than 40 years of follow-up, men who were overweight or obese at age 8, but returned to normal weight at age 20, were 38% more likely to develop cancer compared to those of normal weight throughout development (adjusted hazard ratio). [aHR] 1.38, 95% CI: 1.09-1.75), reported Jenny Kindblom, MD, PhD, of the University of Gothenburg in Sweden.
Men who were overweight at 8 years and remained overweight at 20 years faced a 66% higher cancer risk (aHR 1.66, 95% CI 1.18-2.33), according to findings presented in the obesity week annual meeting.
“A trajectory of childhood overweight is associated with an increased risk of obesity-related cancer, independent of subsequent BMI.” [body mass index] trajectory,” said Kindblom medpage today. “The finding here is new.”
For the study, the researchers tracked 36,566 men born between 1945 and 1961 in Sweden, who were conscripted into conscription when it was required for men. Of these, 6.3% were overweight at 8 years and 7.4% were overweight at 20 years. (The team calculated BMI for those ages using data for ages 6.5 to 9.5 years and 17.5 to 22.0 years.)
During the median follow-up period of 41.3 years, 1,562 men (4.3%) were diagnosed with obesity-related cancers, including oral, esophageal, gastric, colorectal, liver, thyroid, gallbladder, pancreas, male breast and kidney, as well as melanoma, meningioma, lymphoma, multiple myeloma and leukemia. Of them, 570 died.
Absolute cancer risks were highest in those who were overweight at both 8 years and 20 years (6.7%), followed by those who were overweight at 8 years but returned to normal weight by 20 years (5 .4%), those who had normal weight at 20 years. both ages (4.2%), and those with normal weight at 8 years but overweight at 20 years (4.1%).
“Regardless of your young adult BMI at age 20, being overweight at age 8 increases your risk of obesity-related cancers,” Kindblom said.
In another analysis, men who were overweight at 8 years were 51% more likely than others to develop cancer (aHR 1.51, 95% CI 1.26-1.80), and those who were overweight at 20 years they were 25% more likely (aHR 1.25, 95% CI 1.05-1.49).
The researchers adjusted the statistics for year of birth, country of birth, and educational level. “There are some more confounding factors that we would have loved to be able to adjust for, such as lifestyle factors and being overweight later in adulthood,” Kindblom said.
He noted that other studies have linked childhood obesity to cancer in later life, including a 2021 study which linked a higher childhood BMI to a 24% higher risk of cancer mortality. “However, previous studies have not been able to study childhood BMI independently of young adult BMI. What we have done is new: assess overweight at 8 years of age independently of young adult overweight.”
What might explain the excess risk of cancer in men who lost extra childhood weight by age 20?
“My guess is that when BMI is high early in life, there’s a window of time for programming, perhaps mediated by IGF [insulin growth factor]-1/insulin or perhaps other factors, causing adverse physiological changes that lead to obesity-related cancer risk,” Kindblom said.
The study was funded by the Swedish Research Council and the Heart-Lung Foundation.
Kindblom and the co-investigators reported that they had no competing interests to declare.