Overweight and obesity during adolescence increase the risk of renal cell carcinoma (RCC), according to a new study.
In a study of 238,788 Swedish men (mean age 18.5 years) who underwent mandatory military conscription assessment from 1969 to 1976, each 1 kg/m2 increase in body mass index (BMI) during adolescence was associated with a significant 6% increased risk of RCC, after adjusting for age and health status at conscription, blood pressure, and other possible confounders, Anna Landberg, of Örebro University in Örebro, Sweden, and colleagues reported in the International Journal of Cancer.
In addition, compared with normal weight men (reference), men who were overweight or obese had a significant 1.8- and 2.9-fold increased risk of RCC, respectively.
“The link between overweight/obesity and RCC appear to be already established during late adolescence,” the authors concluded. “Prevention of unhealthy weight gain during childhood and adolescence may thus be a target in efforts to decrease the burden of RCC in the adult population.”
Landberg and her collaborators followed the men through linkage to the Swedish Cancer Registry to identify new diagnoses of RCC. During a mean follow-up o 35.4 years, 266 men received a diagnosis of RCC at a mean age 49.4 years.
The investigators defined normal weight as a BMI (in kg/m2) of 18.5 or higher but less than 25, overweight as a BMI of 25 or higher but less than 30, and obesity as 30 or greater.
Strengths of the study include the large sample size, prospective design, and long follow-up, the authors noted. They also acknowledged limitations, pointing out, for example, that the maximum age at the end of follow-up was 57 years. The incidence of RCC increases with age, reaching a plateau at around age 70 years, thus, their follow-up period does not cover the ages with the highest incidence rates, they pointed out. “The aetiology of our cases of early-life RCC could differ from those occurring later in life, and the results may therefore not be directly generalizable to older populations,” they wrote.
Lack of data on smoking is another potential weakness, the authors stated, noting that a previous meta-analysis found an increased relative risk of RCC among people who ever smoked compared with lifetime never-smokers.
Landberg A, Fält A, Montgomery S, et al. Overweight and obesity during adolescence increases the risk of renal cell carcinoma. Int J Cancer. 2019; published online ahead of print.