US Data Reveals Colorectal Cancer Rates Rising Across Successive Generations
New cohort tracking shows later generations face higher cancer risks at all ages, prompting renewed calls for early screening.
A 2026 analysis of United States data indicates that colorectal cancer rates are increasing across successive birth cohorts, affecting both younger and older age groups. The study challenges the prevailing notion that rising incidence is solely attributable to detection bias, noting that mortality rates are also climbing. While various factors such as obesity, ultra-processed foods, and environmental exposures are proposed as causes, no single culprit has been identified by experts.
The analysis, which re-plotted data from Downham et al. and Siegel et al., reveals that later generations born after 1950 have higher colorectal cancer rates at all ages compared to earlier generations. Prior to 1950, later generations enjoyed lower rates across all phases of their lives, but this pattern reversed in the 1950 to 1960 period. The author utilised a plot digitiser to re-analyse data, tracking specific birth cohorts over time rather than just age bands, to demonstrate this cohort effect.
This trend of rising cancer in later generations is not unique to colorectal cancer. Data from Sung et al. indicates that other cancers, including uterine, gallbladder, kidney, liver, pancreas, and thyroid, are also rising in younger people in later generations. However, colorectal cancer is highlighted in public health discourse because it is highly treatable if detected early via screening, unlike pancreatic or thyroid cancer where screening benefits are less clear or treatments are limited.
Previous hypotheses for the rise in colorectal cancer in young people include general health issues such as obesity and diabetes, ultra-processed foods, bad meat consumption, microbiome changes, and environmental exposures. However, experts do not agree on a single cause. Some proposed causes, such as air pollution and tobacco, have actually fallen in rich countries, weakening their case as primary drivers of the recent rise, while others remain mechanistic speculation.
The author recommends colorectal cancer screening, citing its high treatability when detected early. When caught early, colorectal cancer is often treatable with surgery alone, allowing a quick return to normal activities. Screening methods include colonoscopy, sigmoidoscopy, and stool tests, though it is not yet known which is superior. The analysis underscores that screening is better than not screening, regardless of the specific method chosen.
