Bruce W R, Eyssen G M, Ciampi A, Dion P W, Boyd N
Cancer. 1981 Mar 1;47(5 Suppl):1121-5. doi: 10.1002/1097-0142(19810301)47:5+<1121::aid-cncr2820471310>3.0.co;2-k.
As a result of many studies in descriptive and analytic epidemiology, in animal carcinogenesis, and in the direct examination of body fluids for mutagens/carcinogens, it is possible to develop a list of dietary factors that may be associated with the high rate of colon cancer and related cancers in Western countries. This paper is concerned with the design of intervention studies to clarify which of these factors is important. The size of such intervention trials is influenced primarily by two factors: the incidence of the disease outcome studied in a control population and the magnitude of risk reduction in a treated group. Calculations based on a variety of assumptions suggest that a randomized trial in which cancer mortality is measured as the outcome of the intervention in a healthy population is probably too costly to be justified by current evidence linking the disease to diet. However, precursor lesions can be considered as an alternative outcome. The choice of the precursor lesion depends on the link to the disease in question, the prevalence of the lesion in the population, and the ease of detection. Recent developments in the application of endoscopic methods and in the description of the pathologic process leading to cancer suggest the use of gastrointestinal polyps as "precursor lesions" as the outcome of a trial. We illustrate these points with a protocol for a study in progress, a randomized double-blind study of the effect of ascorbic acid and alpha-Tocopherol on the rate of recurrence of colorectal polyps.
通过描述性和分析性流行病学、动物致癌作用以及直接检测体液中的诱变剂/致癌物等诸多研究，有可能列出一份与西方国家结肠癌及相关癌症的高发病率相关的饮食因素清单。本文关注的是设计干预研究以阐明这些因素中哪些是重要的。此类干预试验的规模主要受两个因素影响：对照人群中所研究疾病结局的发生率以及治疗组中风险降低的幅度。基于各种假设的计算表明，在健康人群中以癌症死亡率作为干预结局进行的随机试验可能成本过高，目前将该疾病与饮食联系起来的证据无法证明其合理性。然而，癌前病变可被视为一种替代结局。癌前病变的选择取决于与所讨论疾病的关联、该病变在人群中的患病率以及检测的难易程度。内镜方法应用的最新进展以及对导致癌症的病理过程的描述表明，可将胃肠道息肉作为试验结局的“癌前病变”。我们用一项正在进行的研究方案来阐述这些要点，该方案是一项关于抗坏血酸和α -生育酚对大肠息肉复发率影响的随机双盲研究。
