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At least 505 records · Page 28Linked to original sources
PubMed2007

Combined CT colonography and 18F-FDG PET of colon polyps: potential technique for selective detection of cancer and precancerous lesions.

OBJECTIVE: The purpose of this study was to determine the feasibility of imaging the colon with fused CT colonography (CTC) and 18F-FDG PET and to correlate the findings with the histologic features of polyps. SUBJECTS AND METHODS: Eighteen patients with suspected colorectal polyps enrolled in this prospective study. Before colonoscopy, 17 of the patients underwent a combination of FDG PET and CTC. CTC consisted of 4-MDCT merged with PET. PET of the abdomen and pelvis was performed after each CTC scan. One radiologist and one nuclear medicine physician in consensus analyzed PET and CTC fusion data. PET standard uptake value was correlated with the findings at histologic examination of polyps. Patient feasibility was defined as the ability to tolerate prolonged scanning with good colonic distention. Technical feasibility was determined by how closely anatomically matched polyps overlapped on fusion images. RESULTS: Seventeen of 18 patients tolerated scanning. Eighty-five percent of colon segments were optimally distended. Twenty-three of 27 FDG-avid polyps measuring 10 mm or more had excellent overlap at fusion imaging. PET depicted 23 of 39 premalignant polyps and even showed increased tracer activity associated with four small tubular adenomas (4-6 mm). Sixteen benign polyps (10-25 mm) were not depicted on PET. All nine cases of cancer (tumors measuring 11-60 mm) were detected with both PET and CTC. The standard uptake value of malignant tumors ranged from 4 to 20 (mean, 9). However, six benign flat polyps did not exhibit FDG avidity. CONCLUSION: The novel combination of CTC and PET was feasible in 17 of 18 patients and allowed excellent image correlation in 23 of 27 proven polyps measuring 10 mm or more on PET-CTC fusion. This technique shows promise in accurate anatomic correlation of both malignant and premalignant lesions evaluated with FDG PET.

Adolescent↗
PubMed2002

Treatment with argon plasma coagulation reduces recurrence after piecemeal resection of large sessile colonic polyps: a randomized trial and recommendations.

BACKGROUND: Recurrence is frequent after piecemeal snare resection of large sessile colorectal polyps. The aim of this study was to evaluate the safety and efficacy of argon plasma coagulation (APC) in preventing recurrence when applied to the edge and base of the polypectomy site after apparently complete piecemeal resection. METHODS: Patients with large (>1.5 cm) sessile polyps removed by piecemeal snare cautery were placed into 2 groups. The first consisted of patients with polyps believed by the endoscopist to be completely excised. These patients were randomized to either no further therapy (control) or to APC of the rim and any residual mucosal or submucosal tissue in the base of the polypectomy site. The second group comprised patients in whom polyps, as judged by the endoscopist, were incompletely excised by snare polypectomy; APC was routinely applied without randomization to all visible remaining adenomatous tissue. Follow-up colonoscopy was performed within 3 months and 1 year; biopsy specimens were taken routinely from the resection site and further polypectomy was performed as indicated. RESULTS: There were fewer recurrences after APC in the randomized group (1/10 APC, 7/11 no APC; p = 0.02). In the group with initial incomplete snare polypectomy, recurrence was detected at 3 months in 6 of 13 despite APC. One patient was hospitalized with abdominal pain and minor rectal bleeding but required no intervention. There were no other episodes of significant late bleeding caused by piecemeal polypectomy. One patient was referred for surgery after unsuccessful endoscopic management. CONCLUSIONS: In patients with apparent complete endoscopic snare resection of large adenomas, postpolypectomy application of APC reduces adenomatous recurrence.

Aged↗
PubMed1983

Immunohistological study of precancerous mucus modification in human distal colonic polyps.

The M1 antigens associated with gastric fucomucins, oncofetal markers of the distal colonic mucosa, were demonstrated to be more closely associated with adenomas [92 of 139 (66%)] than with invasive adenocarcinomas [27 of 218 (12%)]. They were always expressed in tumors containing the M3 antigen normally associated with the intestinal mucus. The M1 antigens, present in 100% of hyperplastic polyps (30 of 30), were not specific for a particular histological type of adenoma but were found to be more closely associated with those showing a villous differentiation [41 of 47 (87%)] than with those having a tubular pattern [51 of 92 (55%)]. The presence of these M1 antigens depended neither on the size nor on the degree of cytological atypia of the nodular adenomas. However, M1 antigens were found in 94% of the adenomas (35 of 37) concomitant with adenocarcinomas; in contrast, only 56% of adenomas (55 of 102) observed on noncancerous mucosa contained these M1 antigens. As already demonstrated during rat colonic carcinogenesis, mucus modification characterized by the presence of M1 antigens could represent early molecular changes occurring before malignant transformation related to a chemical carcinogen. These M1 antigens might be regarded as early precancerous markers of an oncofetal type, associated with human distal colonic mucosa.

Adenocarcinoma↗
PubMed1982

Endoscopic argon laser photocoagulation of small sessile colonic polyps.

The availability of flexible quartz wave ¿uides allowing introduction of argon laser energy through endoscopes suggests the possibility of ablation of colonic mucosal lesions by this technique. To ascertain the effects of the argon laser on the colon, penetration depth and perforation studies were conducted in dogs. At 250 joules/cm2 energy density, less than 50% muscularis externa injury was noted in 29 of 42 lesions. No perforation was noted. Healing was complete in 8 days. The time required for deliberate perforation with the catheter firmly pressed against the wall of a distended inflated colon using 2 W argon laser applied continuously was 41 +/- 13 sec, N = 53. In a human study of 15 small sessile polyps ablated by laser and the colon examined 4 days later at colectomy, no penetration of the laser beneath the submucosa was noted. In 11 patients with Gardner's syndrome 211 polyps have been removed in 18 treatments without complication. These encouraging results suggest the continued study of this endoscopic modality in the treatment of mucosal lesions of the colon.

Animals↗
PubMed2002

Colon polyps and cancer.

The superiority of colonoscopy to double-contrast barium enema in detecting neoplasia was finally demonstrated in 2000, but colonoscopic surveillance programs are still based on short-term observations and are mostly inadequate, despite the prospective design of the trials. The evaluation of the diagnostic accuracy of virtual colonoscopy is in progress, but its appropriate place in clinical gastroenterology has not yet been defined. There is now solid evidence that screening with fecal occult blood testing (FOBT) not only reduces the mortality from colorectal cancer, but also that the incidence is substantially reduced after removal of the precursor lesions. Feasibility studies for population screening are ongoing. A once-only sigmoidoscopy will probably not be an optimal method of screening, but may be added to a program with FOBT. Molecular stool screening is attractive, but still experimental. Colonoscopy is not attractive as an initial screening instrument, despite its high diagnostic accuracy, and should only be used for screening high-risk individuals. Genetic methods are playing an increasing role in defining prognostic markers for intestinal neoplasia, and it is recommended that information services should be established for the public. Chemopreventive studies have revealed that dietary fiber supplementation may not reduce the risk of adenomas; the opposite seems to be true for aspirin and non-aspirin NSAIDs, which are active in the early phase of carcinogenesis. New techniques for optimizing diagnostic and therapeutic colonoscopy have been introduced.

Colonic Neoplasms↗
PubMed1998

Enrichment of the more hydrophilic bile acid ursodeoxycholic acid in the fecal water-soluble fraction after feeding to rats with colon polyps.

We recently showed that feeding the cytoprotective bile acid ursodeoxycholic acid (UDCA) to rats resulted in significant reduction in polyps and especially cancers, both in number and size (D. L. Earnest et al., Cancer Res., 54: 5071-5074, 1994). Because fecal secondary bile acids [particularly deoxycholic acid (DCA)] are considered to promote formation of colon adenomas and cancer, we have now attempted to find a relationship between polyp reduction and fecal secondary bile acids after feeding UDCA to these rats. We examined the fecal bile acids in rats with polyps and compared them with fecal bile acids in control rats and also determined the bile acid composition in fecal aqueous phase, which is in direct contact with the colon epithelium and may be physiologically more active. Treatment with azoxymethane did not significantly alter fecal bile acid composition in the rats. Cholic acid feeding resulted in greatly increased proportions of DCA (82% of total bile acids versus 18% in control rats). On the other hand, UDCA feeding significantly reduced the proportion of fecal DCA (2% in control rats fed UDCA and 3% in rats also treated with azoxymethane). In control rats, 96% of the bile acids were present in the water-insoluble fraction and 4% in the water-soluble fraction. The major insoluble bile acids included DCA and hyodeoxycholic acid (73% of total bile acids). In contrast, the muricholic acids were concentrated in the soluble fraction (37%). When 0.4% UDCA was added to the diet, lithocholic acid increased in the insoluble fraction (40 versus 1%), but the hydrophilic UDCA and muricholic acids were enriched in the water-soluble fraction (37 and 43%, respectively). Thus, the hydrophobic bile acids were distributed predominantly in the water-insoluble fraction, whereas the hydrophilic bile acids were distributed preferentially in the water-soluble fraction. These data suggest that UDCA may prevent colon tumors and polyps by countering the toxic effect of DCA and enhancing the possible cytoprotective effects of UDCA and muricholic acids in the water-soluble fraction in the feces of rat.

Animals↗
PubMedDate not supplied

Small colon polyps: the primary physician's dilemma.

This case report and literature review is presented to alert primary care physicians performing flexible sigmoidoscopy and limited colonoscopy to the malignant potential of even diminutive polyps. The term "polyp" refers to any circumscribed mass of tissue that arises from mucosa and protrudes into the lumen of the gastrointestinal tract. The significance of this lesion in the rectum and colon is its propensity for malignant change. Although small polyps in the region of the rectum tend to be hyperplastic and those more proximal tend to be adenomas with a significant malignant potential, there is no way to distinguish them visually; hence, all need to be biopsied. The following case report shows the necessity of identifying neoplastic lesions within diminutive polyps (less than 1 cm). Standard biopsy technique usually removes these lesions; nevertheless, when histology confirms the presence of adenoma or carcinoma, the patient requires additional evaluation of the entire large intestine and more frequent follow-up examinations.

Adenocarcinoma↗
PubMed1989

Differential expression of the Lewis Y antigen defined by monoclonal antibody C14/1/46/10 in colonic polyps.

The expression of Le(y) (Lewis(y) Hapten), a difucosylated type 2 blood group-related antigen, in colorectal lesions was studied by using the monoclonal antibody C14. In normal colonic mucosa, strong staining has been observed in the terminal ileum, cecum, and ascending colon with minimal staining in the rest of the colon and rectum. Eighty-three percent of adenomas expressed Le(y), with 70% showing an increased expression of Le(y) compared with normal tissue. Only 25% of metaplastic (nonneoplastic) polyps showed an increased expression of Le(y). The expression of Le(y) in adenomas was correlated with both size and degree of epithelial dysplasia of the adenomas and also showed an association with histologic type. No correlation was found with the location and morphology of the adenomas. The most strongly related parameter was the degree of dysplasia. All adenomas with severe dysplasia showed increased expression of Le(y), with 83% showing marked expression. This finding was irrespective of their size or type. Adenomas which did not exhibit severe dysplasia showed increased expression in 66% of cases, but only 18% showed marked expression. These findings show that the expression of Le(y) in colorectal lesions is associated with features related to malignant potential. Le(y) expression may provide useful prognostic information in the assessment of colorectal polyps.

Adenoma↗