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Malignant colorectal adenoma

In this issue, Chapman and colleagues report the longterm outcome of the treatment of malignant adenomas identi®ed by a large scale screening study carried out in Nottingham. Polypectomy is an effective treatment in the majority of cases. The treatment of early malignancy by local excision is currently relevant, given the available techniques not only of endoscopic polypectomy but also endoanal resection and transanal endoscopic microsurgery. While there are certain differences in the indications for these, particularly in the clinical circumstances, the basic premise for local treatment is the same, and depends on pathological considerations. Haboubi & Scott review this whole question and show that it is possible to identify high and low risk cases, likely or not already to have regional lymphatic involvement. It is essential for clinicians not only to be aware of these criteria, but also to be clear on the histopathological diagnosis of malignancy. An adenoma becomes a carcinoma only when dysplastic (adenomatous) tissue breaches the muscularis mucosae to invade the submucosa. The term carcinoma-in-situ is confusing. It is used by some pathologists to describe severe dysplasia in an adenoma, but since this is con®ned to the mucosa, the neoplasm remains benign, having not penetrated the muscularis mucosae. The role of the endoscopist seems to be vital, in that complete excision judged endoscopically appears to be a major determinant of subsequent cancer-speci®c outcome. As with so many management dilemmas in medicine, a multidisciplinary approach is likely to lead to the optimal outcome.