Post-polypectomy Surveillance for Reducing Colon Cancer Incidence and Mortality

项目摘要 结直肠癌（CRC）是美国癌症死亡的第二大原因。研究 一致表明，筛查降低了CRC发病率和死亡率的风险。筛查的有效性 通常归因于癌前息肉和可治愈癌症的检测和去除。以通常 在实践中，对许多在基线时切除息肉的患者进行的常规随访包括重复监测 结肠镜检查，以检测和切除额外的息肉和癌症。然而， 结肠镜检查对息肉切除的基线结肠镜检查的监测尚不清楚。事实上，先前的研究 没有关注监测的有效性，也没有具体确定 基线息肉切除术后的系统监测可降低结直肠癌发生或死亡的风险 癌症，相比之下，没有监测。尽管存在知识上的差距，但目前的指南建议常规 结肠镜检查对大多数息肉患者有监测作用。由于结肠镜检查是患者的负担， 与出血等风险相关，并且成本高昂，因此必须确定监测是否可以减少 CRC风险。我们的具体目标是确定息肉切除术后监测结肠镜检查是否减少 CRC发病率（目标1）和死亡率（目标2）。为了实现这些目标，我们将利用以前建立的 在退伍军人部接受结肠镜检查并切除息肉的40多万人队列 事务部（VA）。使用病例队列设计，所有由VA中央癌症中心确定的CRC患者， 登记处，由国家死亡指数确定的所有致命CRC患者，以及随机抽样的 那些在基线时切除息肉的人将被选入研究。我们将使用医疗记录 审查以确定监测结肠镜检查的暴露情况并测量可能影响CRC的其他因素 风险观察到的监测结肠镜检查的发生率和时间将使用时间- 依赖暴露变量，表征息肉切除术后监测指南的依从性。CRC 发病率，以及CRC死亡率将在暴露于与未暴露于 监测结肠镜检查，考虑可能影响CRC风险的其他因素。

PROJECT SUMMARY Colorectal cancer (CRC) is the 2nd leading cause of cancer death in the United States. Research has consistently shown that screening reduces risks for CRC incidence and mortality. Effectiveness of screening has generally been attributed to detection and removal of precancerous polyps and curable cancers. In usual practice, routine follow up for many patients with polyps removed at baseline includes repeat surveillance colonoscopy to detect and resect additional polyps and cancer. However, the incremental benefit of surveillance colonoscopy over baseline colonoscopy with polyp removal is unclear. Indeed, prior research has not focused on effectiveness of surveillance and has not specifically determined whether a clinical strategy of systematic surveillance after baseline polypectomy reduces the risk of developing or dying from colorectal cancer, compared to no surveillance. Despite this gap in knowledge, current guidelines recommend routine surveillance colonoscopy for the majority of patients with polyps. Since colonoscopy is a burden on patients, associated with risks such as bleeding, and costly, it is imperative to establish whether surveillance reduces CRC risk. Our Specific Aims are to determine whether post polypectomy surveillance colonoscopy reduces CRC incidence (Aim 1) and mortality (Aim 2). To accomplish these aims, we will utilize a previously established cohort of over 400,000 individuals who had colonoscopy with polyp removal within the Department of Veterans Affairs (VA). Using a case-cohort design, all individuals with incident CRC identified by the VA Central Cancer Registry, all individuals with fatal CRC identified by the National Death Index, as well as a random sample of those who had polyps removed at baseline will be selected for study inclusion. We will use medical record review to determine exposure to surveillance colonoscopy and measure other factors that may influence CRC risk. Observed occurrence and timing of surveillance colonoscopy delivered will be summarized using a time- dependent exposure variable that characterizes adherence to post-polypectomy surveillance guidelines. CRC incidence, as well as CRC mortality will be compared among individuals exposed versus unexposed to surveillance colonoscopy, taking into account other factors that may influence CRC risk.