Risk exposures in early life and incidence of early-onset colorectal cancer across countries

INTRODUCTION: Globally, the incidence of early-onset colorectal cancer (EoCRC) is increasing, indicating substantial changes in risk exposures. However, little is known about the environmental risk factors for EoCRC in young populations. METHODS: CRC incidence and risk factors data (1990-2019) were extracted from the GBD 2019. Age-standardised incidence of EoCRC and summary exposure value (SEV) of risk factors were estimated with the GBD world population standard using direct method. Early-life exposures were estimated as the gross domestic product (GDP) per capita, the socio-demographic Index (SDI) and the SEV of risk factors in previous decades and at age of 0-4, 5-9, 10-14 and 15-19 years. Average annual percent changes (AAPC) and their 95% confidence interval (CI) were calculated by Joinpoint regression. Associations between risk exposures and incidence were examined at national level by weighted linear or non-linearity regression. RESULTS: The global age-standardized incidence of EoCRC increased from 3.05 (95%CI, 3.03-3.07) per 100 000 in 1990 to 3.85 (95%CI, 3.83-3.86) per 100 000 in 2019. The incidence was higher in countries with high socioeconomic level, but increased drastically in countries in East Asia and Caribbean, particularly in Jamaica [AAPC: 5.1% (95%CI: 3.2, 7.0)]. The GDP per capita, SDI, and SEV of iron deficiency, alcohol use, high body mass index and child growth failure in earlier years were more likely to be associated with the incidence in 2019. Exposures in four age windows in early-life were significantly associated with the incidence, particularly for the exposures at age of 15-19 years. Similar association patterns were found in both gender. CONCLUSIONS: The global, rapidly rising incidence of EoCRC highlights the importance to screen and control the cancer in young populations. The associated risk factors at country level in early life suggest the contribution of the early-life exposures. KEY MESSAGES: • Incidence of EoCRC is increasing globally, which was most notable in countries or regions that are undergoing rapid demographic and epidemiological transitions. • This study demonstrates significant associations of economical and life-style factors in early-life with the incidence of EoCRC at country level.