Samadder N Jewel, Pappas Lisa, Boucherr Kenneth M, Smith Ken R, Hanson Heidi, Fraser Alison, Wan Yuan, Burt Randall W, Curtin Karen
Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA.
Department of Medicine (Gastroenterology), University of Utah, Salt Lake City, Utah, USA.
Am J Gastroenterol. 2017 Sep;112(9):1439-1447. doi: 10.1038/ajg.2017.193. Epub 2017 Jul 11.
Colonoscopy is widely recommended for colorectal cancer (CRC) screening, but evidence to guide the optimal frequency of repeat screening examination is limited. We examined the duration and magnitude of the risk of developing CRC, following a negative colonoscopy in those at average risk and those with a first-degree family history of CRC.
A cohort of Utah residents aged 50-80 years who had a negative colonoscopy between 1 January 2001 and 31 December 2011 was identified using the Utah Population Database. Patients were followed from the time of the index colonoscopy until diagnosis of CRC, death, migration out of state, repeat colonoscopy, or end of the study period. CRC incidence after the index colonoscopy was compared with that of the state population by standardized incidence ratios (SIRs).
A cohort of 131,349 individuals at average risk with a negative colonoscopy was identified. Compared with the state population, a negative colonoscopy was associated with SIRs of 0.15 (95% confidence interval (CI): 0.08-0.23) at 1 year, 0.26 (95% CI: 0.19-0.32) at 2-5 years, 0.33 (95% CI: 0.22-0.43) at 5-6 years, and 0.60 (95% CI: 0.44-0.76) at 7-10 years for CRC following the index colonoscopy. In a secondary analysis involving only patients with a first-degree relative with CRC, patients had a significantly lower incidence of CRC only for the first 5 years of follow-up (SIR 0.39, 95% CI: 013-0.64). There was also a difference in the risk of proximal (SIR 0.72, 95% CI: 0.45-0.98) and distal (SIR 0.51, 95% CI: 0.30-0.72) colon cancers at 7-10 years following a negative colonoscopy.
The risk of developing CRC remains decreased for at least 10 years following the performance of a negative colonoscopy. However, the lower incidence of CRC in those with a family history of CRC differed in magnitude and timing being limited primarily to the first 5 years of follow-up and of lesser magnitude than that in the overall cohort.
结肠镜检查被广泛推荐用于结直肠癌（CRC）筛查，但指导重复筛查最佳频率的证据有限。我们研究了平均风险人群和有CRC一级家族史人群在结肠镜检查结果为阴性后发生CRC的风险持续时间和风险程度。
利用犹他州人口数据库确定了一组年龄在50 - 80岁之间、在2001年1月1日至2011年12月31日期间结肠镜检查结果为阴性的犹他州居民。从首次结肠镜检查时开始对患者进行随访，直至诊断出CRC、死亡、迁出该州、再次进行结肠镜检查或研究期结束。通过标准化发病比（SIRs）将首次结肠镜检查后的CRC发病率与该州人群的发病率进行比较。
确定了一组131349名平均风险且结肠镜检查结果为阴性的个体。与该州人群相比，首次结肠镜检查后1年时，阴性结肠镜检查与SIR为0.15（95%置信区间（CI）：0.08 - 0.23）相关；2 - 5年时为0.26（95% CI：0.19 - 0.32）；5 - 6年时为0.33（95% CI：0.22 - 0.43）；7 - 10年时为0.60（95% CI：0.44 - 0.76）。在仅涉及有CRC一级亲属的患者的二次分析中，患者仅在随访的前5年CRC发病率显著较低（SIR 0.39，95% CI：0.13 - 0.64）。在结肠镜检查结果为阴性后的7 - 10年，近端结肠癌（SIR 0.72，95% CI：0.45 - 0.98）和远端结肠癌（SIR 0.51，95% CI：0.30 - 0.72）的风险也存在差异。
在进行阴性结肠镜检查后的至少10年内，发生CRC的风险仍然降低。然而，有CRC家族史者CRC发病率较低在程度和时间上有所不同，主要限于随访的前5年，且程度低于总体队列。
