Colorectal cancer: chances for prevention through screening

Interventions: Group 1: Colorectal cancer patients: interview, blood sample collection, tumor tissue sample collection, medical records
Group 2: Control participants with no colorectal cancer: interview (if denied, offer of self-administered questionnaire), blood sample collection, medical records
Primary outcome(s): 1) At what age should the first screening examination take place?
2) What time intervals between screening examinations (notably screening endoscopy) are reasonable?
3) Should there be different screening intervals for different risk groups?
Study Design: Allocation: ; Masking: ; Control: ; Assignment: ; Study design purpose: prevention

干预措施：
组1：结直肠癌（colorectal cancer）患者：访谈、血液样本采集、肿瘤组织样本采集、病历调取
组2：无结直肠癌对照参与者：访谈（若参与者拒绝访谈，则提供自填式调查问卷）、血液样本采集、病历调取
主要结局指标：
1）首次筛查检查（screening examination）应于哪个年龄启动？
2）各类筛查检查（尤其是筛查内镜检查（endoscopy））之间的合理间隔时长应为多少？
3）不同风险人群是否应设置差异化的筛查间隔？
研究设计：
分配方案：；设盲情况：；对照设置：；分组方式：；研究设计目的：预防