Childhood Body Mass Index Plays a Role in Kidney Cancer Risk as an Adult

Birth weight, height and childhood body mass index (BMI) are associated with adult renal cell carcinoma (RCC), meaning they could be valuable predictors for a person’s risk of disease, according to new research findings published in the European Journal of Epidemiology.

Having a high BMI as an adult is an established risk factor of RCC, but the researchers wanted to see if this risk factor early in life was also associated with the disease. Moreover, kidney cancer accounts for about 2% of newly diagnosed tumors and 90% of malignant kidney tumors are RCC and being able to understand a person’s risk early in life could lead to better prevention practices.

The researchers examined data from 301,418 children from the Copenhagen School Health Records Register born between 1930-1985 and looked at birth weight and measured heights and weights at ages 7-13. Rare cases of childhood RCC were excluded from the data. They followed the data of these patients through their date of RCC diagnosis, death, emigration, loss to follow-up or the end of the study. Nearly 230,000 individuals studied were eligible for the birth weight analysis.

“Among men and women, positive associations were generally observed between childhood BMI and RCC, with a tendency towards a stronger association with increasing childhood age,” the researchers wrote. “Compared to children with a normal BMI at both ages 7 and 13 years, children with normal BMI at age 7 and overweight at age 13 years had a 1.7-fold increased risk of RCC later in life.”

Children with a normal BMI at age 7 and overweight at age 13 also had a higher risk of RCC than children who were overweight at ages 7 and 13 years old.

The observed children that changed from an above-average BMI at age 7 to an average BMI at 13 years old had a lower risk of RCC than children with an average BMI change between 7 and 13, according to the researchers. However, children consistently overweight between the ages of 7 and 13 did not have an increased risk for RCC.

“Adjustment for birth weight had little influence on the results, thus suggesting that the observed associations were not due to an effect of children with a high BMI also having a high birth weight,” explained the researchers.

Looking at height, the researchers found that children who were persistently taller between 7 and 13 had a higher risk of RCC in adulthood compared to those with an average height in that same age range. Those that had a significant increase of height between 7 and 13 also had a higher risk of RCC in adulthood compared with children who remained at an average height in this age range.

Researchers found no significant difference between boys and girls, even when adjusted for BMI and birth weight. In birth weight, the researchers found a positive association with RCC, however, they found no interaction between risk of RCC from birth weight compared with BMI and height between the ages of 7 and 13.

“We found that children with a high birth weight, a high BMI, gain in BMI, or a tall height, respectively, had higher risk of developing RCC later in life,” the researchers concluded. “Our findings indicate that RCC may originate earlier in life than previously thought and suggest that new explorations into the mechanisms underlying these associations should be undertaken.”