Adenomatous polyps of the colon and rectum. An international panel reports.
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Laser-induced autofluorescence has been used to discriminate normal from adenomatous colonic mucosa. However, few studies to date have studied the origin of colonic autofluorescence. Using confocal microscopy (excitation wavelength 488 nm), we have shown that autofluorescence at this wavelength is present predominantly in the lamina propria of normal mucosa but in the epithelium in adenomatous and hyperplastic polyps. The intensity ratio of epithelial cell to lamina propria fluorescence was significantly lower (P < 0.0001) in normal mucosa (0.52 +/- 0.01) compared with either adenomatous (1.6 +/- 0.2) or hyperplastic polyps (1.7 +/- 0.15). However, the ratios were not significantly different between hyperplastic and adenomatous polyps. Thus, confocal microscopy enables the detection of the sites of autofluorescence within colonic mucosa and the quantitation of differences in fluorescence between different tissue types.
598 colorectal polyps were removed by therapeutic colonoscopy from 377 patients, of both sexes, between 1 and 88 years old, most of them with lower digestive symptoms. The polyps were unique in 67.37% and multiple in 32.63% of patients, and mostly located in rectum and sigmoid colon; 42.14% were pedunculated, 33.95% sessile++/sub-pedunculated, and 23.91% sessile in shape. In 51% the size was over 10 mm in diameter. Histologically, 68.68% were of epithelial neoplastic type: 60.91% adenoma; 6.42% adenoma with adenocarcinoma, and 1.35% polypoid carcinoma. 30.64 were epithelial non-neoplastic type: 20.32% hyperplastic polyp, and 0.51% hyperplastic polyp with tubular adenoma. Two patients (0.53%) had lower digestive hemorrhage immediately after the polypectomy. The complications were controlled with conservative measures without blood transfusion.
Nonsteroidal antiinflammatory drugs (NSAIDs) have considerable potential as chemopreventive agents for colorectal cancer. Recent case-control drug surveillance and large cohort studies found that patients with regular aspirin use had a reduced incidence of colorectal cancer and/or decreased death rate from this disease. Several different NSAIDs reduce formation of both colon adenomatous polyps (the precursor lesion of colon cancer) and cancers in experimental animals given known carcinogens. Perhaps most convincing are reports that the NSAID sulindac promotes regression and inhibits recurrence of adenomatous colon polyps in patients with adenomatous polyposis coli. The best characterized pharmacologic effect of the NSAIDs is their reduction of prostaglandin synthesis by inhibiting prostaglandin synthetase PGE2, which catalyzes the formation of prostaglandin precursors from arachidonic acid. Several lines of evidence are contrary to the concept that inhibition of prostaglandin synthesis is central to the NSAIDs' chemopreventive effects. Relatively high levels of prostaglandins have been reported to inhibit tumor cell growth both in vivo and in vitro, and to inhibit differentiation in some tumor cell lines. We evaluated comparative chemopreventive effects on colon tumor formation in an azoxymethane (AOM)-induced colon carcinogenesis rat model using the NSAIDs piroxicam, sulindac, and sulindac sulfone, a metabolite of sulindac which lacks the anti-prostaglandin synthetase activity typically associated with NSAID-induced gastrointestinal toxicities. The results demonstrate that sulindac sulfone, a compound lacking anti-prostaglandin synthetase activity, inhibits AOM-induced colon cancer in rats. Substantial dose-dependent reductions in both tumor burden and tumor multiplicity were observed in the sulindac sulfone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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In an endoscopic screening study of rectosigmoidal polyps in a defined normal population aged 50-59 years, polyps 5 mm or larger in diameter were removed by diathermic snare resection for histological examination. Histological examination was possible in 50 of 55 polyps removed during colonoscopy from 27 men and 17 women. Of these polyps 41 (82%) were adenomas--12 with moderate dysplasia, 1 with severe dysplasia, and 2 with intramucosal carcinoma. In addition, a small ulcerating carcinoma, Dukes stage A, was found. A greater extent of dysplasia was found in rectosigmoidal adenomas in women, whereas more polyps were found in both distal and proximal parts of the colon among men. The size of adenomas and degree of dysplasia were unrelated to color of the lesions.
It is important for the general surgeon to have a clear idea of what is a malignant polyp and factors determining its clinical management. A malignant polyp is either sessile or pedunculated and harbors an invasive carcinoma which means that malignant cells have penetrated into or through the muscularis mucosae. Carcinoma in situ, intramucosal carcinoma, superficial carcinoma, carcinoma within the the mucosa or lamina propria are terms commonly used that must be distinguished from true invasive malignancy. These polyps should be treated by complete polypectomy and followed up as in a benign polyp. A polyp with invasive carcinoma requires careful evaluation to make a decision if simple polypectomy is sufficient treatment or whether surgical treatment is indicated. This decision is based on the risk factors such as a residual/recurrent tumour and the risk of lymph node metastases. We present a current review of the literature on the subject.
We designed a study to evaluate the fecal carrier rate of Streptococcus bovis in patients with endoscopically proven colonic polyps. Benign polyps (n = 63), i.e., hyperplastic, inflammatory, and juvenile, had a similar fecal carrier rate as the normal control colons. Colons with polyps that are at increased risk for malignant degeneration (n = 62), i.e., tubulovillous and villous adenomas, and colons with carcinoma (n = 18), had a statistically significant increase (p less than 0.05) in the fecal carrier rate for S. bovis over the benign colon group. Overall, the incidence of S. bovis carriage in all colons with polyps was intermediary between normal colons and colons with carcinoma although the numbers did not achieve statistical significance.
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