Objective To estimate benefits and harms of different colorectal cancer screening strategies, stratified by (baseline) 15-year colorectal cancer risk.
Design Microsimulation modelling study using MIcrosimulation SCreening ANalysis-Colon (MISCAN-Colon).
Setting A parallel guideline committee (BMJ Rapid Recommendations) defined the time frame and screening interventions, including selection of outcome measures.
Population Norwegian men and women aged 50-79 years with varying 15-year colorectal cancer risk (1-7%).
Comparisons Four screening strategies were compared with no screening: biennial or annual faecal immunochemical test (FIT) or single sigmoidoscopy or colonoscopy at 100% adherence.
Main outcome measures Colorectal cancer mortality and incidence, burdens, and harms over 15 years of follow-up. The certainty of the evidence was assessed using the GRADE approach.
Results Over 15 years of follow-up, screening individuals aged 50-79 at 3% risk of colorectal cancer with annual FIT or single colonoscopy reduced colorectal cancer mortality by 6 per 1000 individuals. Single sigmoidoscopy and biennial FIT reduced it by 5 per 1000 individuals. Colonoscopy, sigmoidoscopy, and annual FIT reduced colorectal cancer incidence by 10, 8, and 4 per 1000 individuals, respectively. The estimated incidence reduction for biennial FIT was 1 per 1000 individuals. Serious harms were estimated to be between 3 per 1000 (biennial FIT) and 5 per 1000 individuals (colonoscopy); harms increased with older age. The absolute benefits of screening increased with increasing colorectal cancer risk, while harms were less affected by baseline risk. Results were sensitive to the setting defined by the guideline panel. Because of uncertainty associated with modelling assumptions, we applied a GRADE rating of low certainty evidence to all estimates.
Conclusions Over a 15 year period, all screening strategies may reduce colorectal cancer mortality to a similar extent. Colonoscopy and sigmoidoscopy may also reduce colorectal cancer incidence, while FIT shows a smaller incidence reduction. Harms are rare and of similar magnitude for all screening strategies.

目的评估不同结直肠癌筛查策略的益处和危害，按（基线）15 年结直肠癌风险分层。使用微观模拟筛选分析-科隆 (MISCAN-Colon)
设计微观模拟建模研究。
设置平行指南委员会（BMJ快速建议）定义了时间框架和筛选干预措施，包括结果测量的选择。
人口50-79 岁的挪威男性和女性，15 年结直肠癌风险各不相同（1-7%）。
比较四种筛查策略与不进行筛查进行比较：每两年一次或每年一次的粪便免疫化学测试（FIT）或单次乙状结肠镜检查或结肠镜检查，100％的依从性。
主要结果衡量15 年随访期间结直肠癌死亡率和发病率、负担和危害。使用 GRADE 方法评估证据的确定性。
结果经过 15 年的随访，每年进行 FIT 或单次结肠镜检查，筛查 50-79 岁结直肠癌风险为 3% 的个体，将结直肠癌死亡率降低为每 1000 人 6 人。单次乙状结肠镜检查和两年一次的 FIT 将每 1000 人减少 5 例。结肠镜检查、乙状结肠镜检查和每年 FIT 分别将每 1000 人中结直肠癌的发病率降低 10 例、8 例和 4 例。两年一次 FIT 的估计发病率减少为每 1000 人 1 人。据估计，严重伤害为每 1000 人 3 人（每两年一次的 FIT）至每 1000 人 5 人（结肠镜检查）；危害随着年龄的增长而增加。筛查的绝对益处随着结直肠癌风险的增加而增加，而危害则受基线风险的影响较小。结果对指南小组定义的设置敏感。由于与建模假设相关的不确定性，我们对所有估计值应用了低确定性证据的 GRADE 评级。
结论在 15 年期间，所有筛查策略都可以在相似程度上降低结直肠癌死亡率。结肠镜检查和乙状结肠镜检查也可能降低结直肠癌的发病率，而 FIT 的发病率降低幅度较小。对于所有筛查策略来说，危害都很罕见且程度相似。