Why is early-onset colorectal cancer increasing in younger generations?

We’ve found so far that people born after 1950 are more likely to develop colorectal cancer at a younger age than earlier generations. This pattern isn’t explained by aging or increased screening, which suggests something in their early-life environment or lifestyle may be involved [1]. The evidence we’ve reviewed leans toward the idea that factors present during childhood or young adulthood — such as diet, gut bacteria, physical activity levels, or exposure to certain chemicals — could be contributing to this shift. We don’t know exactly which factors are most responsible, and we haven’t seen evidence that rules out any possibilities. Our current analysis shows this trend is consistent across multiple observations, but we haven’t reviewed studies that identify specific causes. What we’ve found so far doesn’t prove any one behavior or exposure is to blame, but it does point to a change in how colorectal cancer develops in younger people compared to the past. This doesn’t mean it’s inevitable — it means the conditions shaping health in early life may be different now than they were for previous generations. If you’re concerned about your risk, paying attention to long-term habits like eating more vegetables, staying active, and avoiding excess processed foods may help, even if we don’t yet know exactly how they connect to this trend.