Effectiveness of Screening Colonoscopy in Reducing Deaths from Colorectal Cancer

描述（由申请人提供）：结肠癌和直肠癌（CRC）是美国癌症死亡的第二大原因，可以在早期发现，更容易治愈，甚至可以使用现有的筛查技术来预防。尽管美国的一些专家组认为结肠镜检查是标准检查，但目前只有有限的直接证据支持结肠镜检查在平均风险成人中越来越多地用于筛查。结肠镜检查比其他筛检有更高的风险和费用。最近的研究报告称，结肠镜检查并不能降低右侧结肠癌的死亡率，右侧结肠癌是乙状结肠镜检查不到的部分。然而，这些发现是有争议的，因为该研究无法区分筛查和诊断用途，也无法准确评估结肠镜检查的完整性。该项目的目标是通过提供证据来证明结肠镜检查是否在实践中实现了所谓的好处，从而为临床和政策决策提供信息。主要的具体目的是评估筛查结肠镜检查在降低平均风险成人CRC死亡率方面的有效性，与不进行筛查相比，总体上和分别用于右侧和左侧癌症。我们的次要目的是：1)确定结肠镜检查的完整性对其有效性的影响；2)比较筛查结肠镜与乙状结肠镜的疗效。我们将采用病例对照设计，在一个研究联盟癌症研究网络（CRN）的3个地点接受治疗的历史队列中嵌套。这些站点为其成员提供从筛查到临终关怀的完整连续癌症护理，并提供有关CRC筛查的信息，这些信息可与大量种族和社会经济不同的人的诊断和病因特异性死亡率数据联系起来。我们将在2007年至2014年间确定至少1200例结直肠癌死亡病例，这些患者在诊断之日年龄为52岁或以上，每个患者在每个健康计划中根据年龄、性别和入组史随机选择两名对照。我们将确定癌症诊断前至少10年的筛查史，区分筛查和诊断程序，使用标准化的目标图表回顾和其他来源。样本量将为单独评估位于右结肠的肿瘤提供足够的力量。该项目将由一支经验丰富的跨学科团队执行，该团队代表流行病学、病例对照方法学、生物统计学、胃肠病学和初级保健。团队成员是CRC筛查研究和政策的国家领导者。该项目与现有的NCI和CRN目标相协调：1)开发提供临床、政策相关信息的方法和途径；2)为CRC筛查的临床和公共卫生决策提供信息。该应用程序还响应了NCI的优先事项，即提高对用于筛查CRC（一种“健康差异状况”）的测试的有效性和比较有效性的理解，并实现了2010年健康人减少癌症死亡的目标。

DESCRIPTION (provided by applicant): Cancers of the colon and rectum (CRC), the second leading cause of cancer death in the US, can be detected at an early, more curable, stage or even prevented using available screening techniques. Although some expert groups in the US consider colonoscopy to be the standard, there is currently only limited direct evidence to support its increasing use for screening in average risk adults. Colonoscopy has higher risks and costs than other screening tests. Recent studies reported that colonoscopy did not reduce mortality from right-sided colon cancers, the part of the colon that is beyond the reach of sigmoidoscopy. However, those findings were controversial because that study was unable to distinguish screening from diagnostic uses or accurately assess the completeness of colonoscopies. This project's goal is to inform clinical and policy decisions by providing evidence to show whether the purported benefits of colonoscopy are realized in practice. The primary specific aim is to estimate the effectiveness of screening colonoscopy in reducing death from CRC among average-risk adults when compared to no screening, overall and separately for right- and left-sided cancers. Our secondary aims are to: 1) determine the impact of the completeness of colonoscopy examinations on its effectiveness; and 2) compare the effectiveness of screening colonoscopy relative to sigmoidoscopy. We will use a case-control design nested in an historical cohort of persons receiving care at 3 sites participating in a research consortium, Cancer Research Network (CRN). These sites provide the full continuum of cancer care to their members ranging from screening through end of life care, and provide access to information on CRC screening that can be linked to diagnosis and cause-specific mortality data on large numbers of racially and socioeconomically diverse persons. We will identify at least 1,200 cases of CRC deaths between 2007 and 2014 among enrollees who were 52 years or older at the date of the diagnosis, each matched within each health plan to two randomly selected controls based on age, sex and enrollment history. We will identify screening history for a minimum of 10 years prior to cancer diagnosis, differentiating screening from diagnostic procedures, using standardized targeted chart reviews and other sources. The sample size will provide sufficient power for separate evaluations of tumors located in the right colon. This project will be carried out by an experienced interdisciplinary team representing epidemiology, case-control methodology, biostatistics, gastroenterology and primary care. Team members are national leaders in CRC screening research and policy. This project is in synergy with existing NCI and the CRN goals to: 1) develop methods and approaches to provide clinical, policy-relevant information; and 2) inform clinical and public health decisions on CRC screening. This application is also responsive to the NCI's priority to improve understanding of the effectiveness and comparative effectiveness of tests used in screening for CRC, a "health disparity condition", and addresses Healthy People 2010 goals to reduce cancer death.