Fiber and Colorectal Adenomas: A Pooling Project

描述（由申请人提供）： 据估计，2003年将有147 500例结肠直肠癌确诊病例，57 100例死于这种疾病。因此，阐明可预防的结直肠肿瘤的危险因素是一项重要的任务。长期以来，人们一直假设饮食可能与结直肠癌的风险有关，并且对保护性饮食成分的研究仍在继续。过去对纤维进行了深入的研究，但结果模棱两可。麦麸纤维（WBF）和息肉预防试验（PPT）是两项大型，随机，III期试验，未能发现谷物纤维补充剂或高纤维，低脂饮食对结直肠腺瘤复发的保护作用。相比之下，最近两项大型研究的结果表明，纤维确实可以保护结肠直肠腺瘤和癌症。因此，关于纤维的作用的模糊性仍然存在。目前工作的假设是，纤维可能具有比以前研究的更具体的保护作用。这些包括，与非晚期腺瘤相比，它可能对晚期腺瘤产生最大的影响，纤维补充剂的效果可能在那些在进入干预试验之前消耗了大量纤维的人中更明显，膳食纤维的来源是一个重要的考虑因素，并且根据性别和结肠中的位置，纤维可能会产生不同的影响。将WBF和PPT试验的研究人群合并为3209名研究受试者的数据提供了研究这些因素的绝佳机会。这一大规模研究所提供的统计功效将使纤维与结直肠肿瘤之间的关联得到进一步澄清。如果发现某些群体可能从纤维中获得更大的益处，那么可以提出针对这些群体的公共卫生建议，并预防结直肠腺瘤的复发。

DESCRIPTION (provided by applicant): There will be an estimated 147,500 colorectal cancer cases diagnosed and 57,100 deaths from this disease in 2003. Therefore, the elucidation of preventable risk factors for colorectal neoplasia is an essential undertaking. It has long been hypothesized that diet may be associated with risk of colorectal cancer, and the search for the protective dietary components continues. Fiber has been studied intensively in the past with equivocal results. The Wheat Bran Fiber (WBF) and Polyp Prevention Trials (PPT) were two large, randomized, Phase Ill trials that failed to find a protective effect of either a cereal fiber supplement or a high-fiber, low-fat diet on colorectal adenoma recurrence respectively. In contrast, the results of two large studies recently indicated that fiber does confer protection from colorectal adenomas and cancer. Therefore, ambiguity with regard to the role of fiber remains. The hypothesis of the current work is that fiber may have more specific protective effects than previously investigated. These include that it may exert the greatest effect on advanced adenomas as compared to non-advanced, that the effect of fiber supplementation may be more pronounced in those who had consumed higher quantities of fiber prior to entry into the intervention trials, that the source of dietary fiber is an important consideration, and that there may be differential effects of fiber depending on gender and location in the colon. Pooling the study populations from the WBF and PPT trials provides an excellent opportunity to investigate these factors with data from 3209 study participants. The statistical power afforded by this large study size will enable further clarification of the association between fiber and colorectal neoplasia. If it is found that certain groups may receive greater benefit from fiber, then public health recommendations can be made which target these groups and prevent the recurrence of colorectal adenomas.