Centre for Medical Imaging, University College London, London, UK; St Mark's Academic Institute, St Mark's Hospital, Harrow, London, UK.
Centre for Medical Imaging, University College London, London, UK.
Lancet Gastroenterol Hepatol. 2018 May;3(5):326-336. doi: 10.1016/S2468-1253(18)30032-3. Epub 2018 Feb 19.
CT colonography is highly sensitive for colorectal cancer, but interval or post-imaging colorectal cancer rates (diagnosis of cancer after initial negative CT colonography) are unknown, as are their underlying causes. We did a systematic review and meta-analysis of post-CT colonography and post-imaging colorectal cancer rates and causes to address this gap in understanding.
We systematically searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. We included randomised, cohort, cross-sectional, or case-control studies published between Jan 1, 1994, and Feb 28, 2017, using CT colonography done according to international consensus standards with the aim of detecting cancer or polyps, and reporting post-imaging colorectal cancer rates or sufficient data to allow their calculation. We excluded studies in which all CT colonographies were done because of incomplete colonoscopy or if CT colonography was done with knowledge of colonoscopy findings. We contacted authors of component studies for additional data where necessary for retrospective CT colonography image review and causes for each post-imaging colorectal cancer. Two independent reviewers extracted data from the study reports. Our primary outcome was prevalence of post-imaging colorectal cancer 36 months after CT colonography. We used random-effects meta-analysis to estimate pooled post-imaging colorectal cancer rates, expressed using the total number of cancers and total number of CT colonographies as denominators, and per 1000 person-years. This study is registered with PROSPERO, number CRD42016042437.
2977 articles were screened and 12 studies were eligible for analysis. These studies reported data for 19 867 patients (aged 18-96 years; of 11 590 with sex data available, 6532 [56%] were female) between March, 2002, and May, 2015. At a mean of 34 months' follow-up (range 3-128·4 months), CT colonography detected 643 colorectal cancers. 29 post-imaging colorectal cancers were subsequently diagnosed. The pooled post-imaging colorectal cancer rate was 4·42 (95% CI 3·03-6·42) per 100 cancers detected, corresponding to 1·61 (1·11-2·33) post-imaging colorectal cancers per 1000 CT colonographies or 0·64 (0·44-0·92) post-imaging colorectal cancers per 1000 person-years. Heterogeneity was low (I=0%). 17 (61%) of 28 post-imaging colorectal cancers were attributable to perceptual error and were visible in retrospect.
CT colonography does not lead to an excess of post-test cancers relative to colonoscopy within 3-5 years, and the low 5-year post-imaging colorectal cancer rate confirms that the recommended screening interval of 5 years is safe. Since most post-imaging colorectal cancers arise from perceptual errors, radiologist training and quality assurance could help to reduce post-imaging colorectal cancer rates.
St Mark's Hospital Foundation and the UK National Institute for Health Research via the UCL/UCLH Biomedical Research Centre.
CT 结肠成像术对结直肠癌具有高度敏感性，但尚不清楚结直肠癌的间隔或成像后发生率（首次阴性 CT 结肠成像后诊断癌症），也不清楚其根本原因。我们对 CT 结肠成像后和成像后结直肠癌发生率及其原因进行了系统评价和荟萃分析，以解决这一理解上的差距。
我们系统地检索了 MEDLINE、Embase 和 Cochrane 对照试验中心注册库。我们纳入了 1994 年 1 月 1 日至 2017 年 2 月 28 日期间发表的随机、队列、横断面或病例对照研究，使用符合国际共识标准的 CT 结肠成像术来检测癌症或息肉，并报告成像后结直肠癌的发生率或提供足够的数据以计算其发生率。我们排除了所有 CT 结肠成像术都是因为结肠镜检查不完全而进行的研究，或者如果 CT 结肠成像术是在了解结肠镜检查结果的情况下进行的研究。对于需要进行回顾性 CT 结肠成像图像复查和每个成像后结直肠癌的原因的研究，我们联系了组成研究的作者以获取额外的数据。两位独立的审查员从研究报告中提取数据。我们的主要结局是 CT 结肠成像后 36 个月的结直肠癌患病率。我们使用随机效应荟萃分析来估计成像后结直肠癌的总发生率，以总癌症数和总 CT 结肠成像术数作为分母，并以每 1000 人年表示。这项研究在 PROSPERO 注册，编号 CRD42016042437。
筛选了 2977 篇文章，有 12 项研究符合分析条件。这些研究报告了 19867 名患者的数据（年龄 18-96 岁；在 11590 名有性别数据的患者中，6532 名[56%]为女性），随访时间平均为 34 个月（范围 3-128.4 个月），CT 结肠成像术检测到 643 例结直肠癌。随后诊断出 29 例成像后结直肠癌。成像后结直肠癌的总发生率为 4.42（95%CI 3.03-6.42）/100 例检出癌症，相当于每 1000 次 CT 结肠成像术或每 1000 人年有 1.61（1.11-2.33）或 0.64（0.44-0.92）例成像后结直肠癌。异质性较低（I=0%）。28 例成像后结直肠癌中有 17 例（61%）归因于感知错误，在回顾性检查中可见。
与结肠镜检查相比，CT 结肠成像术在 3-5 年内不会导致检查后癌症的发生率增加，5 年的低成像后结直肠癌发生率证实推荐的 5 年筛查间隔是安全的。由于大多数成像后结直肠癌是由于感知错误引起的，因此放射科医生的培训和质量保证可以帮助降低成像后结直肠癌的发生率。
圣马克医院基金会和英国国民健康保险制度通过 UCL/UCLH 生物医学研究中心提供。
