Premalignant Lesions of the Colon
Cancer of the colon and rectum is the second most common cancer in men and women in North America. Early diagnosis results in detection of early stage tumours with a high probability of cure. Several studies document the efficacy of screening for the early detection of colorectal cancer; however, it...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
1990-01-01
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| Series: | Canadian Journal of Gastroenterology |
| Online Access: | http://dx.doi.org/10.1155/1990/857961 |
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| Summary: | Cancer of the colon and rectum is the second most common
cancer in men and women in North America. Early diagnosis results in detection
of early stage tumours with a high probability of cure. Several studies document
the efficacy of screening for the early detection of colorectal cancer; however, its incidence is so high chat screening the entire older adult population is not
feasible. Thus, attempts have been made to focus screening on patients at higher
than average risk for colorectal carcinoma; these include patients with predisposing
conditions or premalignant lesions of the colon. Common predisposing
conditions include previous resection of an adenoma or carcinoma, a family
history of colorectal carcinoma, and ulcerative colitis of more than IO years'
duration. The most important premalignant lesion is the colonic adenoma. Such
lesions must be removed in their entirety and examined histologically to exclude
the presence of carcinoma. Approximately 51 % of patients with colonic
adenomas removed by endoscopic polypectomy will be found to have a carcinoma
within the polyp. If a pedunculated adenoma containing invasive carcinoma
can be removed with a clear stalk margin, the risk of nodal metastasis is
very low, probably less than 2%. In contrast, sessile lesions containing carcinoma
already show invasion into the submucosa of the underlying bowel wall with a
significant risk of nodal metastasis. Segmental colonic resection is rarely necessary
for management of the patient with carcinoma arising in a pedunculated
adenoma, but it is often justified for the patient with carcinoma in a sessile lesion.
Dysplasia arising in ulcerative colitis is another important premalignant lesion
that can be detected by colonoscopy with biopsy. The presence of high grade
dysplasia in a patient with longstanding ulcerative colitis is an indication for
colectomy. |
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| ISSN: | 0835-7900 |