摘要：

It is frequently stated that all but a few arise in , in turn initiated by mutation. Moderation of this view is now required. The proportion of that arises in a is likely to be around 70% [39,61]. The pre-eminence of the -model has been influenced by two factors: (1) the need to avoid overtreatment of innocent lesions, and (2) the absence of a convincing alternative mechanism. The latter position has changed in recent years. Collectively, the alternative pathways may account for the of up to 30% of . The alternative pathways are difficult to observe in clinical practice because the precursors may be either inconspicuous or show rapid evolution following the establishment of genetic instability. As a concept, the polyp-sequence is entrenched in both specialized and student texts. This is unfortunate, because progress in prevention and early detection will be delayed by the failure to adopt a critical and nondogmatic approach to the of . The advent of DNA chip technology will catalyze the of revised paradigms. Specifically, modern genomics will allow polyps and to be grouped within pathogenic pathways on the basis of shared gene expression profiles. The era of molecular medicine has dawned for .

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