Global Incidence Trend of Early-Onset Obesity-Related and Non-Obesity-Related Cancers

The global rise in obesity prevalence and the incidence of early-onset cancer (diagnosed between 20 and 49 years of age) is a serious public health concern. We, therefore, evaluated the recent global trends in the incidence of early-onset obesity-related cancers and compared them to those of non-obesity-related cancers. We obtained age-standardized incidence rates of early-onset cancers diagnosed between 2000 and 2012 in 44 countries from the Cancer Incidence in Five Continents database. Using joinpoint regression models, we calculated the average annual percentage changes (AAPCs) and their corresponding 95% confidence intervals (95% CIs) for combined and individual categories of obesity-related cancers (11 and 9 cancer types in females and males, respectively) and non-obesity-related cancers (12 cancer types in both females and males). Differences in the AAPC were assessed by comparing 95% CIs, where nonoverlapping 95% CIs were considered statistically significantly different. We observed statistically significant positive AAPCs for early-onset obesity-related cancers in all available countries combined among females (global AAPC, 4.3%; 95% CI, 4.1–4.6%) and males (global AAPC, 1.4%; 95% CI, 1.2–1.7%). When analyzed by countries, we observed statistically significant positive AAPCs in 26 countries among females and 11 countries among males. AAPCs for early-onset obesity-related cancers were statistically significantly higher than those of non-obesity-related cancers in several regions, especially North America and Oceania. In conclusion, this study indicates that the incidence of early-onset obesity-related cancers exhibited a more pronounced increasing trend than non-obesity-related cancers among both sexes in many countries and regions.