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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The frequent coexistence of adenoma with primary carcinoma of the colon and their association with higher incidences of both synchronous and metachronous carcinomas offers only circumstantial evidence that adenomas are premalignant lesions. Detailed histopathologic investigations, however, have documented the transition from adenoma to carcinoma. Although the common, minute adenomatous polyp has a low potential of malignancy, the risk increases with size, villous architecture and degree of epithelial dysplasia. Furthermore, the association of dysplasia, which shares many adenomatous features with carcinoma in patients with chronic ulcerative colitis, and the inevitable development of adenomatous polyps followed by carcinoma of the colon and rectum in patients with familial polyposis further support this concept. Most colorectal malignant lesions, therefore, are believed to progress through the adenoma to carcinoma sequence. Moreover, histochemical investigations have demonstrated that abnormalities of DNA content, enzyme activities, CEA expression and mucin composition are shared by both adenoma and carcinoma. Thus, the malignancy potential of adenoma of the colon and rectum is reflected not only in the overt histologic transition to carcinoma, but in the disruption of the genetic and biochemical control mechanisms of cellular function as well.
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PMID:The adenoma to carcinoma sequence. 216 17

Remarkable advances in the understanding of specific inherited and acquired genetic events that are important in colonic carcinogenesis have occurred in the last several years. Studies of the population genetics of colon cancer have determined that the gene responsible for familial adenomatous polyposis (FAP), and Gardner's syndrome has been localized on the long arm of chromosome 5 and have more clearly defined the importance of genetic influences in 'sporadic' colon cancer. Studies of the molecular genetics of colon cancer have identified acquired alterations in oncogenes such as the K-ras gene and in putative tumor suppressor genes such as the FAP gene on chromosome 5, the p53 gene on chromosome 17, and the DCC gene on chromosome 18, which appear to mediate important steps in the adenoma-dysplasia-carcinoma sequence. Some of these research advances (FAP gene carriage) are already being used clinically to identify individuals at risk for colon cancer, and they offer great promise for the future of both prevention and therapeutic programs.
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PMID:Lessons from the genetics of colon cancer. 217 30

Activation of c-Ki-ras by point mutation within exon 1 was studied in 33 specimens of dysplastic gastrointestinal lesions or of cancers presumed to arise from dysplasia. Samples were obtained from patients with underlying ulcerative colitis or Barrett's esophagus, two diseases associated with dysplasia and increased rates of colonic or esophageal adenocarcinoma, respectively. Genomic DNA was amplified using primers bounding this exon in the polymerase chain reaction. Polymerase chain reaction products were analyzed by direct dideoxy sequencing. Three point mutations in codon 13 of c-Ki-ras were found, all in colonic specimens (two high-grade dysplasias and one adenocarcinoma arising in ulcerative colitis). No point mutations were observed in the second exon of c-Ki-ras or in and around codons 12, 13, and 61 of c-N-ras and C-Ha-ras in a partial sampling of the specimens. These data indicate that ras family protooncogene activation is an uncommon event at this level of malignant progression in these disease states. Carcinogenesis in ulcerative colitis and Barrett's esophagus may proceed via different pathways than in sporadic colon cancer, perhaps involving loss or inactivation of suppressor genes.
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PMID:Activation of c-Ki-ras in human gastrointestinal dysplasias determined by direct sequencing of polymerase chain reaction products. 218 99

Mutations in the first exon of the c-Ki-ras protooncogene were analyzed in carcinomas and dysplasias from patients with sporadic colon cancer and chronic ulcerative colitis by a combination of histological enrichment, cell sorting, polymerase catalyzed chain reaction, and direct sequencing. In contrast to sporadic colon carcinomas, where 52% (11 of 21) contained mutations in codon 12, only 1 of 28 samples of ulcerative colitis associated carcinoma or dysplasia contained a c-Ki-ras mutation, despite the presence of aneuploid cell populations. These results suggest that a different genetic pathway for tumor progression may exist between sporadic colon carcinoma and carcinomas arising in chronic ulcerative colitis.
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PMID:c-Ki-ras mutations in chronic ulcerative colitis and sporadic colon carcinoma. 219 96

During a three-year period (1986-1988), 234 colonic brush specimens were received in the authors' laboratory. Nine samples (4%) were deemed unsatisfactory for evaluation because of inadequate cellularity and/or poor fixation. In 11 cases concomitant or follow-up histologic specimens were not available. The remaining 214 specimens included 82 malignant neoplasms, 88 neoplastic polyps (adenomas), and 44 nonneoplastic lesions. Sixty-seven (82%) of malignant neoplasms were correctly diagnosed by brush cytology. Three cases of adenoma with severe dysplasia or in situ carcinoma were diagnosed as adenocarcinoma by cytology. No false-positive diagnoses were made of nonneoplastic lesions. Brush cytology was found to be a more sensitive technique in the diagnosis of colon cancer than endoscopic biopsy (82% and 74% sensitivity, respectively). The combination of the two techniques increased the sensitivity to 90% and improved the overall accuracy of the test. Seventy-one (82%) of the colonic adenomas were correctly diagnosed by cytology. Brush cytology is a convenient, safe, and accurate technique which should be used concurrently with endoscopic biopsy or polypectomy.
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PMID:Brush cytology in the diagnosis of colonic neoplasms. 220 9

In vitro tetraploidy (IVT) in skin fibroblasts cultures measured by flow cytometry was compared with histological type and degree of dysplasia in 22 patients with adenomas of the colon and rectum. Furthermore, IVT was compared with stage and differentiation in 36 patients with carcinoma of the colon and rectum. In vitro tetraploidy in skin fibroblasts was correlated to type as well as dysplasia in adenomas and differentiation in carcinomas but was not correlated to Dukes' stage in carcinomas. Skin fibroblast genetic instability, expressed as increased IVT (IVT+), has been reported to reflect a genetic predisposition to colorectal cancer in the hereditary nonpolyposis colorectal cancer syndrome. Because IVT+, which appears to be associated with the progression of adenomas to carcinomas, also is found in many of the non-syndrome colorectal cancers, we suggest that development of colorectal cancer is considerably influenced by the constitutive genetic instability of the autosomal dominant colorectal cancer syndromes.
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PMID:Correlation between in vitro tetraploidy in skin fibroblasts and development of sporadic colorectal carcinomas. 225 81

Butyrate has induced differentiation in neoplastic cells grown in vitro, among them being colon cancer cell lines. In vivo, only one major study used sodium butyrate in the drinking water and showed an elevation in 1,2-dimethylhydrazine induced colon cancer in rats. Seeking to show that it was the sodium and not the butyrate which was responsible for the enhancement, we fed tributyrin at a 5% level to mice for 48 weeks. Mice experienced normal growth and development at this dose. Analysis of short chain fatty acids in the feces after 6 months in tributyrin feeding showed a 10-fold increase in butyric acid. However no difference in AOM induced focal areas of dysplasia or colonic tumor incidence was observed between tributyrin fed and control mice. At least two conclusions have been reached by this study, (1) that the dietary use of a sodium salt can contribute to the enhancement of chemically induced colon neoplasia and (2) butyrate may be discounted as providing any major therapeutic benefit against colonic tumorigenesis.
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PMID:Dietary butyrate (tributyrin) does not enhance AOM-induced colon tumorigenesis. 235 22

Patients with ulcerative colitis are at greater risk of developing carcinoma of the colon than the general population even if the exact risk cannot be determined. Thus, an effort must be made to find the carcinoma at its inception or better still before it occurs. Dysplasia serves as a premalignant marker in some cases, and a surveillance program serves to find either dysplasia or the carcinoma. Until more specific premalignant changes are identified, endoscopic surveillance with multiple biopsies offers the best protection for the patient with longstanding ulcerative colitis against carcinoma. There is now sufficient evidence that this also pertains to Crohn's disease of the colon.
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PMID:Considerations of surveillance, dysplasia, and carcinoma of the colon in the management of ulcerative colitis and Crohn's disease. 240 76

The LeY determinant, a difucosylated type 2 blood group-related antigen, is a positional isomer of the Leb blood group antigen and a fucosylated derivative of the LeX antigen. The LeX antigen behaves like an oncodevelopmental tumor-associated antigen in human colon cancer, and extended polyfucosyl LeX antigens are more specific for colon cancer tissues than are simple, monofucosyl LeX antigens. The present investigation compared the expression of simple and extended LeY antigens in a variety of malignant and nonmalignant human colonic tissues to gain insight into the normal distribution and cancer-associated expression of these antigens. Monoclonal antibody AH-6, which recognizes the LeY epitope irrespective of its carrier carbohydrate chain, stained the majority of specimens regardless of malignant potential or location within the colon. In contrast, CC-1 and CC-2 monoclonal antibodies, which recognize extended LeY structures, and KH-1, which is specific to trifucosyl LeY, preferentially stained malignant colonic tissues and rarely stained normal colonic mucosae. Mucosa immediately adjacent to cancer usually stained with AH-6 but not with KH-1, CC-1, or CC-2. Extended or trifucosyl LeY antigen expression was limited exclusively to premalignant (adenomatous) polyps and was invariably absent from nonpremalignant (hyperplastic) polyps. Moreover, among adenomatous polyps, extended LeY antigen expression tended to correlate with three parameters of malignant potential: larger polyp size; villous histology, and severe dysplasia. AH-6 failed to distinguish between hyperplastic and adenomatous polyps. In second-trimester fetal colonic mucosa, AH-6 bound to both proximal and distal segments whereas KH-1, CC-1, and CC-2 bound only to proximal segments. We conclude that in human colon, the LeY hapten is an oncodevelopmental cancer-associated antigen and extended LeY antigens are highly specific markers for malignancy and premalignancy.
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PMID:Expression of LeY and extended LeY blood group-related antigens in human malignant, premalignant, and nonmalignant colonic tissues. 242 90

Longstanding ulcerative colitis predisposes to carcinoma of the colon. Argyrophil cell hyperplasia has been observed in association with dysplasia and neoplasia in ulcerative colitis. As the argyrophil cell population includes those cells producing enterglucagon, a hormone thought to stimulate mucosal proliferation, this study was designed to determine whether there was any consistent variation in the argyrophil cell population in longstanding ulcerative colitis. Argyrophil cells were demonstrated by the Grimelius method of silver impregnation in sections of non-tumour bearing mucosa from the rectosigmoid colon of normal bowel, ulcerative colitis with and without tumour, and mucosa adjacent to, and distant from, carcinoma arising in otherwise normal bowel. Cell numbers were expressed as ratios of argyrophil cells per crypt, per mm of epithelium, and per mm of underlying muscularis mucosae. There was marked individual variation within all groups in all parameters. Between groups, the only significant difference was an increase in argyrophil cells per crypt in ulcerative colitis. The significance of this finding is discussed.
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PMID:Variation in the argyrophil cell population of the rectum in ulcerative colitis and adenocarcinoma. 242 63


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