Flexible sigmoidoscopy (FS), which is less invasive, resource intensive and costly than colonoscopy, is among the recommended screening options for colorectal cancer (CRC). Four large randomized trials consistently reported statistically significant, albeit modest effects of screening by FS on CRC incidence. However, their effect estimates included cancers that were already prevalent at recruitment and could not have been prevented by screening. We performed a re-analysis and meta-analysis of two of the trials (including the largest one) to estimate reduction of truly incident cases by a single FS offered between 55 and 64 years of age among the “at risk study population” without prevalent CRC at recruitment. In meta-analyses of data reported after more than 15 years of follow-up, relative risk (95% CI) in intention-to-screen and per-protocol analyses were 0.71 (0.66–0.76) and 0.59 (0.55–0.65) for any CRC, and 0.52 (0.47–0.57) and 0.34 (0.30–0.39) for distal CRC, respectively. These results indicate much stronger effects than those suggested by the original reports and imply that a single screening FS can prevent approximately two out of three distal incident CRC cases within 15 + years of follow-up.

与结肠镜检查相比，可屈性乙状结肠镜检查 (FS) 侵入性较小、资源密集且成本较高，是推荐的结直肠癌 (CRC) 筛查选择之一。四项大型随机试验一致报告了 FS 筛查对 CRC 发病率的统计显着影响（尽管影响不大）。然而，他们的效应估计包括招募时已经流行且无法通过筛查预防的癌症。我们对其中两项试验（包括最大的一项）进行了重新分析和荟萃分析，以估计在“高危研究人群”中，在 55 岁至 64 岁之间提供的单一 FS 所减少的真实事件病例数，而没有普遍存在CRC 在招聘时。在超过 15 年随访后报告的数据的荟萃分析中，意向筛选和符合方案分析的相对风险 (95% CI) 分别为 0.71 (0.66–0.76) 和 0.59 (0.55–0.65)。任何 CRC，远端 CRC 分别为 0.52 (0.47–0.57) 和 0.34 (0.30–0.39)。这些结果表明，效果比原始报告所建议的效果要强得多，并意味着单次筛查 FS 可以在 15 年以上的随访内预防大约三分之二的远端 CRC 病例。