carcinoma and surveillance of colon and rectum after polypectomy: implication for efficacy of colonoscopy

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作者：

CD Chen，MF Yen，WM Wang，JM Wong，TH-H Chen

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摘要：

The disease natural history of colorectal neoplasm regarding two opposing theories, adenoma–carcinoma sequence andcarcinoma theory, is controversial and rarely quantified. The aims of this study are therefore to estimate the dwelling times of adenoma–carcinoma sequence by adenoma size and histological type, takingcarcinoma into account. The efficacy of polypectomy was therefore estimated making allowance for two pathways. A case–cohort design, underpinning a cohort with 13908 subjects (including 10496 normal subjects, 2652 polyps, 760 colorectal cancers) who underwent the first examination of colonoscopy between 1979 and 1998, was devised to estimate parameters associated with two opposing theories by randomly selecting 305 normal subjects, 300 patients with polyps, and 116 colorectal cancers from the cohort. All the 2652 polyps were linked to national cancer registry to ascertain 25 invasive carcinomas after polypectomy. For the five-state model associated with adenoma size, dwelling times of small (0.6–1cm) and large adenoma (>1cm) are 7.75 and 5.27 years for the model without considering, and 17.48 and 15.90 years for the model takingcarcinoma into account. Similar findings are observed for the model associated with histological type. The estimated proportions ofcarcinoma are 31.87% from the model by adenoma size and 27.81% from the model by histological type. Compared to size less than 5mm, patients with adenoma size between 6 and 10mm and patients with adenoma size larger than 1cm have 2.17-fold (0.67–10.74) and 4.25-fold (1.23–14.70), respectively, for the risk of malignant transformation. There are similar findings for the model by histological type. The estimates of overall efficacy of colonoscopy in reducing CRC is 73% for the model allowing forcarcinoma and 88% for the model without consideringcarcinoma theory. The efficacy of diminutive adenoma and small adenoma increases with follow-up years, whereas the efficacy of large adenoma decreases with follow-up years. In conclusion, about 30% of cancers arising fromsequence are demonstrated. This finding, together with the adenoma–carcinoma sequence associated with adenoma size and histological type, is important for the estimation of dwelling times, the efficacy of colonoscopy, and the surveillance of polyp after polypectomy.

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关键词：

adenoma–carcinoma de novo carcinoma dwelling time adenoma size histological type Markov model

DOI：

10.1038/sj.bjc.6601007

被引量：

665