PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Colonic Polyps”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1982

Fecal blood loss in patients with colonic polyps: a comparison of measurements with 51chromium-labeled erythrocytes and with the Haemoccult test.

The quantitative determinations of fecal daily blood loss after intravenous administration of 51Cr-labeled erythrocytes in 44 patients with colonic polyps and in 11 controls were compared with the results of the daily performed Haemoccult test without dietary restrictions. A total of 642 stool specimens was analyzed for 51Cr loss and the Haemoccult test. The mean fecal daily blood loss in the 34 patients with adenomatous polyps of the descending colon and rectosigmoid was 1.36 +/- 0.14 ml/day (mean +/- SEM), in the 10 patients with polyps of the ascending and transverse colon it was 1.28 +/- 0.31 ml/day, and in the 11 controls 0.62 +/- 0.07 ml/day. There was no positive Haemoccult test in the controls. In fecal specimens from patients with polyps in the descending colon and rectosigmoid containing 2.0-3.99 ml blood/day, the Haemoccult-test was positive in 86%. Fecal specimens from patients with polyps in the ascending colon and transverse colon containing equal blood loss yielded a positive Haemoccult test result in 26%. Thus, the positivity of the Haemoccult test is determined by the fecal daily blood loss and the anatomic location of colonic bleeding sites.

Chromium Radioisotopes↗
PubMed2003

Multiple neural network classification scheme for detection of colonic polyps in CT colonography data sets.

RATIONALE AND OBJECTIVES: A new classification system for colonic polyp detection, designed to increase sensitivity and reduce the number of false-positive findings with computed tomographic colonography, was developed and tested in this study. MATERIALS AND METHODS: The system involves classification by a committee of neural networks (NNs), each using largely distinct subsets of features selected from a general set. Back-propagation NNs trained with the Levenberg-Marquardt algorithm were used as primary classifiers (committee members). The set of features included region density, Gaussian and mean curvature and sphericity, lesion size, colon wall thickness, and the means and standard deviations of all of these values. Subsets of variables were initially selected because of their effectiveness according to training and test sample misclassification rates. The final decision for each case is based on the majority vote across the networks and reflects the weighted votes of all networks. The authors also introduce a smoothed cross-validation method designed to improve estimation of the true misclassification rates by reducing bias and variance. RESULTS: This committee method reduced the false-positive rate by 36%, a clinically meaningful reduction, and improved sensitivity by an average of 6.9% compared with decisions made by any single NN. The overall sensitivity and specificity were 82.9% and 95.3%, respectively, when sensitivity was estimated by means of smoothed cross-validation. CONCLUSION: The proposed method of using multiple classifiers and majority voting is recommended for classification tasks with large sets of input features, particularly when selected feature subsets may not be equally effective and do not provide satisfactory true- and false-positive rates. This approach reduces variance in estimates of misclassification rates.

Algorithms↗
PubMed1979

Morphology, anatomic distribution and cancer potential of colonic polyps.

The concept of a polyp-cancer sequence is assuming increasing credibility as a factor in the development of colorectal cancer. Colonoscopy permits most colonic polyps to be endoscopically removed and studied pathologically. Of various polyp types encountered in the colon only neoplastic polyps are regarded as having malignant potential. Neoplastic polyps include tubular adenomas (formerly, adenomatous polyps), villous adenomas and villotubular adenomas (formerly, mixed or tuboglandular polyps). Cancerous changes must penetrate the muscularis mucosae for a polyp to be regarded as clinically malignant. The present report analyzes a series of 5,786 adenomas from over 7,000 polyp endoscopically removed. The largest number of each type of adenoma presented in the sigmoid colon, followed by the descending colon in terms of frequency. In all zones tubular adenomas were most common, villous least. Abnormal cellular change, from dysplasia to carcinoma in situ to invasive cancer was most frequently found in the sigmoid colon and, in all colon sectors, increased as the villous componency of the polyp increased. However, all categories of neoplastic polyps showed malignant changes. Polyp size, long recognized as a factor, was shown to be importantly related to malignant change, but invasive cancer was found even in polyps less than 1 cm in diameter. In addition, the incidence of malignancy rose parallel to the frequency of synchronous and metachronous polyps. A vigorous program for detection and endoscopic removal of colorectal polyps is recommended as a means of reducing the incidence of colorectal cancer.

Adenoma↗
PubMed1975

Fecal bacteriology of colonic polyp patients and control patients.

Feces from 25 subjects with colonic polyps (multiple adenomatous, large single, or single with atypia) and from 25 matched control subjects were studied by detailed quantitative aerobic and anaerobic techniques, using a large battery of culture media and several atmospheric conditions. Over 55% of organisms detected on microscopic count were recovered anaerobically. In several cases, there were significantly different numbers of organisms of specific types recovered from the two different populations studied. However, these differed from organisms with "statistical significance" noted in a previous study from this laboratory involving two different diet groups (Japanese Americans on either a Japanese or a Western diet). Specific differences in bacteriology between groups with different risks of bowel cancer, noted in earlier British studies, were not noted in our present or previous study.

Aerobiosis↗
PubMed1985

Altered collagen in colonic polyps.

By biochemical analysis the molar ratio between hydroxyproline and hydroxylysine as indicator of collagen type were analyzed in normal colons, colonic polyps and carcinomas. Low ratios (type IV) were found in the polyps.

Collagen↗
PubMed1986

Differential expression of difucosyl type 2 chain (LeY) defined by monoclonal antibody AH6 in different locations of colonic epithelia, various histological types of colonic polyps, and adenocarcinomas.

The expression of LeY (Fuc alpha 1----2Gal beta 1----4 [Fuc alpha 1----3]GlcNAc beta 1----R) (in which Fuc is fucose, Gal is galactose, and GlcNAc is N-acetylglucosamine) defined by monoclonal antibody AH6 in various locations of human colonic epithelia, colonic polyps, and adenocarcinomas has been studied. In normal colonic mucosa, strong staining by AH6 was observed in the proximal regions such as the terminal ileum and cecum. The staining was, however, greatly reduced in the epithelia of the ascending colon and became very weak in the epithelia of transverse, descending, and sigmoidal colon as well as the rectum. Of 481 crypts in 40 biopsy samples of the epithelia of normal sigmoidal colon, 421 crypts did not show any staining, and only a weak staining of the lowest crypt area was observed in 60 crypts (12%); of 474 crypts in 40 biopsy samples of normal rectal epithelia, 110 crypts (26%) showed a weak staining. At the fetal stage, the LeY staining was much more intense in all locations of the colon than in corresponding locations of adult epithelia, and staining was observed in the epithelia of the sigmoidal colon and rectum. A strong staining was observed in 24 of 25 cases of colorectal adenocarcinomas, irrespective of their original location. The expression of LeY in polyps was correlated with histological type as well as the degree of dysplasia of the polyps. Of various adenomas examined, tubular adenomas, many of which showed mild or moderate dysplasia and less malignant potentials, displayed the least LeY expression. Tubulovillous and villous adenomas, which have higher malignant potential and showed a higher incidence of severe dysplasia, showed a greater area and intensity of LeY expression. No LeY was detectable in juvenile polyps, and only a very weak staining was observed in the dysplastic area of hyperplastic polyps. The extent and intensity of staining in various adenocarcinomas and adenomas could not be correlated with blood group ABO status of the hosts nor with location of the tumors. These results suggest that LeY in colonic adenocarcinomas and polyps at the distal region of the colon and rectum is a typical oncofetal antigen and is a useful marker for diagnosis of colonic cancer. Its expression in colonic polyps can be correlated with the degree of dysplasia and may indicate the degree of malignant potential of the polyp. Thus, LeY expression in polyps may have prognostic value.

Adenocarcinoma↗
PubMed2001

Three-dimensional computer-aided diagnosis scheme for detection of colonic polyps.

We have developed a three-dimensional (3-D) computer-aided diagnosis scheme for automated detection of colonic polyps in computed tomography (CT) colonographic data sets, and assessed its performance based on colonoscopy as the gold standard. In this scheme, a thick region encompassing the entire colonic wall is extracted from an isotropic volume reconstructed from the CT images in CT colonography. Polyp candidates are detected by first computing of 3-D geometric features that characterize polyps, folds, and colonic walls at each voxel in the extracted colon, and then segmenting of connected components corresponding to suspicious regions by hysteresis thresholding based on these geometric features. We apply fuzzy clustering to these connected components to obtain the polyp candidates. False-positive (FP) detections are then reduced by computation of several 3-D volumetric features characterizing the internal structures of the polyp candidates, followed by the application of discriminant analysis to the feature space generated by these volumetric features. The locations of the polyps detected by our computerized method were compared to the gold standard of conventional colonoscopy. The performance was evaluated based on 43 clinical cases, including 12 polyps determined by colonoscopy. Our computerized scheme was shown to have the potential to detect polyps in CT colonography with a clinically acceptable high sensitivity and a low FP rate.

Algorithms↗
PubMed1984

Neoplastic colonic polyp with extensive squamous metaplasia. Case report.

Extensive squamous metaplasia in neoplastic colonic polyps is rare. This paper describes extensive squamous metaplasia in an adenomatous polyp evolving into adenocarcinoma. The origin of squamous cell carcinoma and adenocanthoma of the colon is not well understood. This case is the only case reported in the literature that demonstrates the development of squamous metaplasia in dysplastic colonic glands, in situ adenocarcinoma, and finally invasive adenocarcinoma of the colon. The pertinent literature is reviewed.

Adenocarcinoma↗
PubMed1996

[Cancerous colonic polyps].

The treatment of cancerous polyps of the colon has not been definitely established. In the present study the authors have brought forth their contribution on the role played by endoscopic polypectomy alone or following a surgical resection. At our endoscopic service during the period from 1985 to 1992, there were 42 polyps diagnosed which after histologic examination showed an infiltrating carcinoma. 22 patients underwent surgery and 16 only an endoscopic polypectomy. The median follow-up was 43.3 months with a minimum period of 18 months. Four patients were lost during follow-up. We have analyzed for prognostic reasons, the type of polyps, the radicality of the polypectomy, the degree of differentiation and the infiltration of lymphatic and/or venous vessels of the polyp. The presence of carcinomal residue and lymphonodal metastases were taken into consideration in patients who underwent surgical resection. The results obtained were not evaluated statistically because of the limited number of patients with an adequately long follow-up. Nevertheless they are in line with those results from the majority of the cases quoted in other literature. In particular these cases which seem to have a favorable prognosis are those in which complete endoscopic polypectomy has coupled with a good degree of differentiation and the absence of infiltration of the lymphatic and venous vessels. In these cases surgery does not seem to have bettered the survival rate.

Aged↗
PubMed1985

An assessment of an immunochemical test for human haemoglobin in the detection of colonic polyps.

It is now widely accepted that malignant tumours of the colon and rectum almost invariably arise from pre-existing adenomatous polyps. If such polyps could be detected and removed colonoscopically before they become malignant, theoretically the incidence of invasive colorectal cancer could be dramatically reduced. The purpose of this study was to determine whether an immunochemical test for faecal occult blood would identify patients with benign colonic polyps. The faecal samples from 121 patients scheduled to undergo colonoscopy were tested by our immunochemical method and the Hemoccult II test. There were nine patients who had malignant colorectal tumours. These were excluded from this study. Twenty-nine were found to have colonic polyps. Fifteen of these had one or more faecal samples which were positive by the immunochemical test. In contrast, there was only one patient who had a positive Hemoccult II test. Fourteen of the remaining 83 patients had positive immunochemical tests. The findings on colonoscopy provided satisfactory explanations in all these cases. Polyps of all sizes and histological type were associated with positive immunochemical tests. It is concluded that the immunochemical test has sufficiently high sensitivity for colonic polyps to make feasible the screening of patients at high risk of developing colonic cancer.

Colonic Polyps↗
PubMed2003

Colon polyps and cytokines: emerging immunological mechanisms.

Cell-mediated immune responses are an essential aspect of tumour-host interactions in colorectal cancers. The progression from precancerous (adenomatous) colon polyps to malignant colorectal cancer depends on a complex pathway involving the activities of activated T lymphocytes. The immune response is initiated when either cytotoxic T lymphocyte (CTL) CD8+ cells or CD4+ T-helper cells recognize the antigen from a human cancer cell. The cell-mediated response is largely initiated and controlled by the actions of various cytokines, which exert profound effects on T cell proliferation, cell-cell adhesion, apoptosis, and host immunity. The existence of an immune response to colon cancer is supported by studies of immunological treatments in humans and transplantable murine cancer models in animals. IL-2, IL-12, IFN-gamma, TNF-alpha, and TRAIL are implicated in enhancing cytotoxic and apoptotic effects in response to colon adenomas. In addition, growth factors, oncogenic cytokines and immunosuppressive factors may play a crucial role in the growth and survival of premaligant colonic tissue. This review aims to increase knowledge of the immunological mechanisms underlying colon tumour progression in the hopes that a greater understanding of the molecular pathways will lead to improved methods of prognosis and treatment.

Adenomatous Polyps↗