Early-Onset Disease Is Reshaping the Global Burden of Colorectal Cancer | Nature Reviews Clinical Oncology
Introduction
Colorectal cancer (CRC) remains the third most commonly diagnosed cancer and the second leading cause of cancer-related mortality worldwide. Although CRC has historically been concentrated in Western high-income countries, its global epidemiology is rapidly changing, with rising incidence now extending across diverse geographic and socioeconomic settings.
Problem Statement
The global rise in CRC is increasingly driven by early-onset disease, particularly in individuals younger than 50 years, challenging traditional assumptions that CRC is predominantly a disease of older adults in high-income populations. This shift cannot be fully explained by inherited susceptibility or expanded screening alone, suggesting that evolving environmental, metabolic and lifestyle exposures are playing a major role in reshaping CRC risk worldwide.
Summary
This review highlights a major epidemiologic transition in CRC, with disease burden increasingly shifting beyond Western high-income countries and disproportionately affecting younger populations. The rise in early-onset CRC, first recognized in the 1990s, is now a global phenomenon and appears to reflect a birth-cohort effect implicating shared generational exposures rather than screening patterns alone. The authors emphasize that while hereditary risk remains important, emerging global CRC trends are more likely driven by non-genetic factors, including Westernized dietary patterns, sedentary lifestyle, obesity, gut microbial disruption and increasing exposure to environmental contaminants associated with rapid urbanization. These exposures may contribute not only to carcinogenesis but also to the distinct biology of early-onset CRC. The review further underscores the potential of integrating genomic, epigenomic and microbiome profiling to better define disease mechanisms and support earlier detection and precision prevention. Importantly, the authors highlight a major evidence gap in low- and middle-income regions, where under-representation in molecular and epidemiologic studies risks widening disparities in CRC prevention and control. This review positions early-onset CRC as a defining global oncology challenge requiring both biologic and public health recalibration.
