A double-edged sword in the very elderly: to screen or not to screen with colonoscopy?

The incidence of colorectal cancer (CRC) increases with advancing age. In 2023, the crude incidence rates of CRC in Korea were 105.6, 129.4, 153.8, 187.3, 236.8 and 271.4 per 100,000 for individuals aged 60–64, 65–69, 70–74, 75–79, 80–84 and ≥85 years, respectively.1 Although routine screening, which facilitates the endoscopic detection and resection of precancerous lesions, reduces CRC-related incidence and mortality, current guidelines generally recommend CRC screening and surveillance only up to the age of 75 years.2 According to the United States (US) guidelines,3 CRC screening in individuals aged 76 to 85 years should be performed selectively, guided by individualized decision-making accounting for overall health status, prior screening history, and personal preferences. These recommendations are based on biological and epidemiological evidence supporting that a lag time of approximately 10 years is required to observe any significant reduction in CRC-related mortality as a net benefit of screening colonoscopy. Thus, discontinuing routine CRC screening should be considered for individuals with a remaining life expectancy of less than 10 years, taking into consideration the procedural risks associated with screening colonoscopy and subsequent treatment for CRC.2

Nevertheless, recent studies have demonstrated potential benefits of screening colonoscopy in adults aged over 75 years. For example, Lee et al.4 evaluated the efficacy and safety of screening colonoscopy in 602 individuals aged ≥75 years. Despite a suboptimal rate of inadequate bowel preparation (29%) assessed by the Boston bowel preparation score as a reference standard,5 the cecal intubation rate reached up to 98%, remaining consistently high even among those aged ≥80 years. The study population revealed a clinically significant diagnostic yield, with CRC and advanced adenomas detected in 0.9% and 6.8% of patients, respectively. This is consistent with the real-world evidence from an Australian surveillance cohort of asymptomatic adults aged 75 years or over, which reported detection rates of 1.6% and 38% for CRC and advanced adenoma, respectively.6 In contrast, the overall incidence of complications was remarkably low at 1.5%, predominantly comprising endoscopically controllable bleeding, even though nearly one third of the population was on antithrombotic agents.4 Notably, the limitations of this single-center, retrospective cohort study warrant cautious interpretation. Selection bias is inherent as health-conscious, proactive individuals with better functional status may have been more likely to undergo screening in this study. The advanced medical infrastructure and expertise available at a tertiary referral center further limit the generalizability of these findings to real practice, particularly in primary care settings. More critically, this study failed to demonstrate the longitudinal efficacy of screening colonoscopy to improve survival in this elderly population with a constrained life expectancy.

A landmark US prospective cohort study to analyze over 56,000 participants confirmed that screening colonoscopy after 75 years of age was associated with significant reductions in CRC incidence (hazard ratio [HR], 0.61) and CRC-related mortality (HR, 0.60), irrespective of the prior screening history.7 However, this survival benefit vanished among individuals with pre-existing cardiovascular disease or multiple comorbid conditions. In one meta-analysis, the pooled incidence of overall colonoscopy-related complications among patients aged ≥80 years was 3.5%, representing a 1.7-fold higher risk compared to those under 80 years.8 In a population-based cohort study, the cumulative incidence of 30-day post-colonoscopy adverse events was 6.8% in patients age ≥75 years, with age ≥75 years identified as an independent risk factor for complications.9 In one retrospective cohort of 8,154 patients aged ≥60 years undergoing screening or diagnostic colonoscopies, we reported that the use of antiplatelet or anticoagulant which are widely used to prevent cardiovascular diseases in older individuals10 and functional frailty, rather than chronological age, were independently associated with 30-day adverse events following colonoscopy.11 The incidence of adverse events in the low-, moderate-, and high-risk groups according to the validated risk prediction model derived from these findings was 0.3%, 2.2%, and 10.7%, respectively,11 supporting personalized decision-making when conducting colonoscopies in older adults.

Consequently, screening colonoscopy in the oldest-old population operates as a true double-edged sword: although it is highly effective in detecting clinically significant advanced neoplasms, it is potentially non-beneficial in frail or very elderly individuals with limited life expectancy. To bridge the gap between technical feasibility and clinical benefit, future management strategies should shift from rigid age-based thresholds towards multidimensional risk stratification. Ultimately, deciding whether to screen for CRC in individuals aged over 75 years should be anchored in structured shared decision-making, carefully balancing individual health priorities, procedural risks, and outcome expectations.