Screening colonoscopy, recommended every ten years, reduces mortality from colorectal cancer (CRC) by early detection of prevalent but undiagnosed CRC, as well as by prevention of CRC by removal of precursor lesions. The aim of this study was to assess the relative contribution of both components to total CRC mortality reduction over time. Using a validated multistate Markov model, we simulated hypothetical cohorts of 100,000 individuals aged 55-64 with and without use of screening at baseline. Main outcomes included proportions of prevented CRC deaths arising from (asymptomatic) CRC already prevalent at baseline and from newly developed CRC during 15-years of follow-up, and mortality rate ratios of screened versus unscreened groups over time. Early detection of prevalent cases accounted for 52%, 30% and 18% of deaths prevented by screening colonoscopy within 5, 10 and 15 years, respectively. Relative reduction of mortality was estimated to be much larger for mortality from incident cancers than for mortality from cancers that were already present and early detected at screening endoscopy and for total CRC mortality (i.e., 88% versus 67% and 79% within 10 years from screening). Reduction of CRC mortality mainly arises from early detection of prevalent cancers during the early years after screening colonoscopy, but prevention of incident cases accounts for the majority of prevented deaths in the longer run. Prevention of incident cases leads to sustained strong reduction of colorectal cancer mortality, possibly warranting an extension of screening intervals.

中文翻译：

---

通过结肠镜检查进行早期检测和癌症预防对降低结直肠癌死亡率的贡献：一项经过验证的模型研究

建议每十年进行一次结肠镜检查，通过早期发现普遍但未确诊的 CRC，以及通过去除前驱病变来预防 CRC，从而降低结直肠癌 (CRC) 的死亡率。本研究的目的是评估随着时间的推移，这两个组成部分对结直肠癌总死亡率降低的相对贡献。使用经过验证的多状态马尔可夫模型，我们模拟了 100,000 名 55-64 岁个体的假设队列，无论是否在基线时进行了筛查。主要结果包括基线时已流行的（无症状）CRC 和 15 年随访期间新发生的 CRC 引起的预防性 CRC 死亡比例，以及随时间推移筛查组与未筛查组的死亡率比率。早期发现流行病例分别占 5 年、10 年和 15 年内通过筛查结肠镜检查避免死亡的 52%、30% 和 18%。据估计，与已存在且在筛查内窥镜检查中早期发现的癌症死亡率以及结直肠癌总死亡率相比，新发癌症死亡率的相对降低幅度要大得多（即，10 年内分别为 88%、67% 和 79%）。筛选）。结直肠癌死亡率的降低主要来自结肠镜检查后早期几年对流行癌症的早期发现，但从长远来看，事件病例的预防占预防死亡的大部分。预防事故病例可以持续大幅降低结直肠癌死亡率，可能需要延长筛查间隔。