Departments of Emergency Medicine, Family Medicine, and Surgery, Yukon-Kuskokwim Delta Regional Hospital, 700 Chief Eddie Hoffman Highway, Bethel, AK 99559, USA.
Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA; Cancer Prevention and Control Program, Arnold School of Public Health, University of South Carolina, Columbia, SC, USA.
Prev Med. 2019 Jan;118:104-112. doi: 10.1016/j.ypmed.2018.10.014. Epub 2018 Oct 24.
Flexible sigmoidoscopy (FS) is the only cancer screening test to lower the risk of death compared to usual care in randomized controlled trials (RCTs). We hypothesize that this unique death reduction is more attributable to prevention of colorectal cancer (CRC) than to early diagnosis. The systematic review of the 2016 US Preventive Services Task Force Evidence Report for CRC Screening was used for selection of RCT studies. A random-effects meta-analysis of five FS trials (N = 458,002) and four fecal occult blood test (FOBT) trials (N = 328,767) was performed using intention-to-screen outcomes for death, CRC incidence, and death attributed to CRC; correlation and linear regression analyses explored the relationships between these outcomes. At 10.5-11.9 years of follow-up FS reduces death (relative risk [RR], 0.975; 95% CI, 0.958-0.992 and reduces CRC incidence (RR, 0.79; 95% CI, 0.74-0.84). Within the FS trials death reduction shows a strong linear correlation with CRC incidence reduction (r, 0.95; 95% CI 0.42-0.99). At 15.6-30.0 years of follow-up FOBT does not reduce death (RR, 1.001; 95% CI, 0.992-1.010) or CRC incidence (RR, 0.96; 95% CI, 0.89-1.02) but does reduce deaths attributed to CRC (RR, 0.84; 95% CI, 0.78-0.91). Clinical trials of screening FS display a dose-response relationship between the magnitude of CRC prevention and the magnitude of death reduction. Prevention of CRC appears to be the major (or sole) mechanism of action for death reduction by FS in clinical trials. Conversely, early diagnosis of CRC does not appear to reduce death.
柔性乙状结肠镜检查（FS）是唯一一种在随机对照试验（RCT）中与常规护理相比降低死亡风险的癌症筛查试验。我们假设这种独特的死亡率降低更多归因于结直肠癌（CRC）的预防，而不是早期诊断。对 2016 年美国预防服务工作组 CRC 筛查证据报告的系统评价用于选择 RCT 研究。使用意向筛查结局对死亡、CRC 发病率和归因于 CRC 的死亡进行了五项 FS 试验（N=458002）和四项粪便潜血试验（FOBT）试验（N=328767）的随机效应荟萃分析；相关性和线性回归分析探讨了这些结局之间的关系。在 10.5-11.9 年的随访中，FS 降低了死亡（相对风险 [RR]，0.975；95%CI，0.958-0.992）和 CRC 发病率（RR，0.79；95%CI，0.74-0.84）。在 FS 试验中，死亡率降低与 CRC 发病率降低呈强线性相关（r，0.95；95%CI 0.42-0.99）。在 15.6-30.0 年的随访中，FOBT 并未降低死亡（RR，1.001；95%CI，0.992-1.010）或 CRC 发病率（RR，0.96；95%CI，0.89-1.02），但降低了归因于 CRC 的死亡（RR，0.84；95%CI，0.78-0.91）。FS 筛查的临床试验显示 CRC 预防的程度与死亡率降低的程度之间存在剂量反应关系。预防 CRC 似乎是 FS 在临床试验中降低死亡率的主要（或唯一）作用机制。相反，CRC 的早期诊断似乎不会降低死亡率。
