Endoscopic Screening and Risk of Colorectal Cancer according to Type 2 Diabetes Status

Abstract

Current recommendations for colorectal cancer screening have not accounted for type 2 diabetes (T2D) status. It remains unknown whether the colorectal cancer-preventive benefit of endoscopic screening and the recommended age for screening initiation differ by T2D. Among 166,307 women (Nurses' Health Study I and II, 1988-2017) and 42,875 men (Health Professionals Follow-up Study, 1988-2016), endoscopic screening and T2D diagnosis were biennially updated. We calculated endoscopic screening-associated hazard ratios (HR) and absolute risk reductions (ARR) for colorectal cancer incidence and mortality according to T2D, and age-specific colorectal cancer incidence according to T2D. During a median of 26 years of follow-up, we documented 3,457 colorectal cancer cases and 1,129 colorectal cancer deaths. Endoscopic screening was associated with a similar HR of colorectal cancer incidence in the T2D and non-T2D groups (P-multiplicative interaction = 0.57). In contrast, the endoscopic screening-associated ARR for colorectal cancer incidence was higher in the T2D group (2.36%; 95% CI, 1.55%-3.13%) than in the non-T2D group (1.73%; 95% CI, 1.29%-2.16%; P-additive interaction = 0.01). Individuals without T2D attained a 10-year cumulative risk of 0.35% at the benchmark age of 45 years, whereas those with T2D reached this threshold risk level at the age of 36 years. Similar results were observed for colorectal cancer mortality. In conclusion, the absolute benefit of endoscopic screening for colorectal cancer prevention may be substantially higher for individuals with T2D compared with those without T2D. Although T2D is comparatively rare prior to the fifth decade of life, the rising incidence of young-onset T2D and heightened colorectal cancer risk associated with T2D support the consideration of earlier endoscopic screening in individuals with T2D.

Prevention relevance: The endoscopic screening-associated ARRs for colorectal cancer incidence and mortality were higher for individuals with T2D than those without T2D. Endoscopic screening confers a greater benefit for colorectal cancer prevention among T2D individuals, who may also benefit from an earlier screening than the current recommendation.