Adolescent obesity may be associated with an increased risk for non-cardia gastric cancer (NCGC), according to the results from a cohort of almost 1.8 million men and women. Even after adjustment for multiple confounders, an obese adolescent body mass index (BMI) remained associated with risk for NCGC in both men and women.
However, according to Zohar Levi, MD, of Rabin Medical Center, Israel, and colleagues, one main limitation of the study was that the cohort of individuals was still young, with a median age of 47 years, at the time of NCGC diagnosis. Results of the study were published in Cancer.
“In the current study, BMI was measured only once at the age of 17 years, and we had no data on weight changes later in life,” they wrote. “Because the adult BMI is not independent of the adolescent BMI and we have evidence of BMI tracking from the age of 17 years to the age of 50 years for a subset of our cohort, it is possible that it is the adult BMI associated with the increased risk and not adolescent obesity or the duration of obesity.”
The study analyzed 1,087,358 Israeli Jewish men and 707,212 Israeli Jewish women who had undergone compulsory physical examination between the ages of 16 and 19 from 1967 to 2002. The researchers linked this data to the national cancer registry and tracked NCGC diagnoses through December 31, 2012.
“A number of mechanisms have been proposed to explain the association between obesity and subsequent cancer development: insulin and insulin-like growth factor signaling pathways, adipokines, inflammation and immune responses, and gastrointestinal microbiota have been suggested as major players,” the researchers wrote.
With a median follow-up of 23.3 years, 515 cases of NCGC were diagnosed. Compared with individuals of normal weight, adolescent obesity was associated with the risk of subsequent NCGC in both men (unadjusted hazard ratio [HR], 1.95; 95% CI, 1.25–3.06) and women (unadjusted HR, 1.78; 95% CI, 1.12–2.83). Adolescent overweight was not associated with risk for NCGC.
The researchers identified several additional factors associated with increased risk for NCGC. Individuals that emigrated from the former Soviet Union (adjusted HR, 2.67; 95% 1.86–3.83), those with a low education level (HR, 1.85; 95% CI, 1.53–2.25), and those with a low residential socioeconomic (SES) class (HR, 1.48; 95% CI, 1.13–1.93) were all at increased risk for NCGC.
The researchers also acknowledged that they lack data on possible confounders such as smoking status, alcohol intake, diet, and H. pylori status.
“The absence of data on the prevalence of H. pylori in our study population might impinge on the association between obesity and NCGC that we report,” the researchers wrote. “Also, as stated previously, our only available SES variable (in addition to education) was the residential SES at adolescence. Because SES is a strong determinant of gastric cancer, it is possible that some residual confounding by SES remained.”