Rectal cell proliferation and colorectal cancer risk level in patients with nonfamilial adenomatous polyps of the large bowel

Article Abstract:

Colorectal cancer is thought to arise from dysplasia, regions of tissue that are clearly abnormal but not cancerous. There is also some indication that even prior to the appearance of dysplasia, colorectal cells in some patients may be proliferating at an abnormally high rate. The rate of proliferation of rectal cells was measured in 119 subjects with different conditions. Twenty-five patients had a single small adenoma (a benign tumor), 22 had several small adenomas, 28 had a single large adenoma, and 22 patients had several adenomas at least one of which was large. The results from these patients were compared with those obtained from 32 patients with colon cancer and 32 control subjects. It should be emphasized that the patients with the adenomas did not have the familial adenomatous polyposis syndrome. Furthermore, among the subjects with abnormalities, the measurements were not made on the abnormal tissues but, rather, on rectal cells that were apparently normal. Cell proliferation was measured by incubating small biopsy specimens with radioactive thymidine; this results in cell DNA becoming radioactive in proportion to the rate that new DNA is being synthesized. When the specimens were examined under the microscope, no differences in the fraction of radioactively labelled cells could be found among the groups. This indicates that the overall rate of cell proliferation was comparable among all the specimens. However, the distribution of proliferating cells within the specimens was not the same for all groups. Among the patients with large adenomas, the proliferating cells were located toward the top of the crypts; in normal intestinal tissues proliferating cells are located near the bottom of the tiny wells called crypts. This abnormal pattern of cell proliferation was also observed in the patients with actual colorectal cancer. These observations suggest that changes in the pattern of cell proliferation within intestinal tissue may help to identify patients with a high risk of developing colorectal cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Risk factors, Physiological aspects, Cell proliferation, Intestinal polyps, Rectum

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Rectal and colonic carcinoids: a clinicopathologic study of 84 cases

Article Abstract:

Colorectal carcinoids, which are circumscribed tumors, have been reported to have a bad clinical course, but there are significant discrepancies between different pieces of research on this subject. To clarify the features of rectal and colonic carcinoids and document their clinical course, 84 cases were reviewed. All but three of these involved carcinoids in the rectum; all 84 were within 20 centimeters of the anus. Histological staining with antibodies for specific enzymes and hormones revealed a range of differing endocrine characteristics of these tumors. Carcinoembryonic antigen (CEA), a tumor marker often used for screening and diagnosis, was present in 24 percent of the tumors, indicating that CEA cannot be used as a distinguishing feature for adenocarcinoma in these cases. When the tumors were examined microscopically for mitoses, which provide a visual estimate of the rate of cell division, few were seen in tumors smaller than 2 cm. Thirty-five patients were available for follow-up at 24 months. Thirty-one had nonmetastasizing tumors; 30 of these were alive and well, while one had died of an unrelated tumor. Four patients had metastatic tumors, of whom one had died after 91 months of follow-up. These numbers indicate a significantly more benign course of development than has been reported by others. This difference may be due to an overly broad definition of carcinoid. In this study, 20 percent of the cases were originally misdiagnosed, which may result in unnecessary surgery. Properly defined carcinoids are limited to the rectum and sigmoid colon, and have an indolent course of development. The proper use of immunohistochemical markers will help to distinguish carcinoids from other more serious tumors of the colon and rectum. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Carcinoid, Carcinoid tumor

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