Adenomatous Polyps of the Colon: Pathobiological and Clinical Features

Normal Colon.- A. Anatomic Considerations.- B. Histology.- Pathology.- A. General Prevalence and Anatomic Distribution.- B. Gross Appearance.- Multiplicity.- Size.- C. Microscopic Features.- Tubular versus Villous Adenomas.- Degree of Dysplasia.- Problems in Grading Dysplasia.- Carcinoma in a Polyp.- Morphometric Studies.- D. Differential Diagnosis.- Hyperplastic (Metaplastic) Polyps.- Mixed Hyperplastic-Adenomatous Polyps.- Juvenile Polyps.- Hamartomatous Polyps.- Polypoid Carcinoma.- Nonepithelial Polyps.- E. The Diminutive Polyp.- F. Other Characteristics of Polyps.- Kinetics.- Electron Microscopy.- Histochemistry.- Markers.- Tissue Culture.- DNA Content.- Doubling Time.- Regression of Polyps.- G. Histogenesis of Polyps.- Adenomatous Polyposes.- A. Familial Polyposis Coli and Gardner's Syndrome.- B. Other Adenomatous Polyposis Syndromes.- C. The Genetics of Adenoma Transmission.- Malignant Potential of Adenomatous Polyps.- A. Association of Polyps and Carcinomas.- Risk Factors for Carcinomas among Polyp-Bearers.- Natural History of Polyps; Metachronous Carcinomas.- Peak Incidences of Adenomatous Polyps and Colorectal Carcinomas.- Metachronous Carcinomas in Subjects with Synchronous Polyps and Carcinomas.- Prevalence of Polyps in Subjects with Colorectal Carcinomas.- Opposing Views.- B. Histological Evidence of Malignant Transformation.- C. Adenomatous Remnants in Carcinomas.- D. Epidemiological Evidence and Etiological Factors.- Sex and Age.- Relationship of Polyps and Colorectal Carcinomas.- Dietary and Other Factors.- Etiology.- E. Findings in Experimental Animals.- Observations.- Genesis of Tumors.- Interpretation of Findings and Relevance to Humans.- F. Alternate Hypotheses of Carcinogenesis.- The Flat Mucosa.- Other Routes.- Nonadenomatous Polyps.- Inflammatory Bowel Disease.- Miscellaneous.- The Field Effect.- Hereditary Nonpolyposis Colorectal Cancer.- G. Conclusions.- Evidence of Malignant Potential of Adenomatous Polyps.- Significance of Malignant Potential of Adenomatous Polyps.- The Problem of the Metachronous Carcinoma.- Detection and Management.- A. Screening, Diagnostic, and Surveillance Techniques.- Principles of Screening.- The At-Risk Population to Be Screened.- Digital Examination of the Rectum.- Stool Blood Tests.- Barium Enema (BE).- Endoscopy.- Proctosigmoidoscopy.- Colonoscopy.- Sensitivity.- Comparisons with Barium Enema.- Effectiveness of Screening.- B. The Malignant Polyp.- The Problem.- Frequency.- Risk Factors for Malignancy in a Polyp.- Size.- Multiplicity.- Villous Component.- Degree of Dysplasia.- Effects of Study Design and Polyp Processing Technique.- Statistical Analysis.- Adverse Outcomes.- Level of Submucosal Invasion by Carcinoma.- Postpolypectomy Therapy.- C. Endoscopic Polypectomy.- How Polyps Are Detected.- Rationale for Detection and Eradication of Polyps.- Manpower and Cost Considerations.- Therapy of Diminutive Polyps.- Polypectomy Technique.- D. Postpolypectomy Surveillance Recommendations.- Recurrent Polyps.- Risk Factors for New Polyps.- Surveillance Schedules.- Effectiveness and Cost of Surveillance.- E. The National Polyp Study.- F. Polyp Registries.- Conclusions.- Glossary and Abbreviations.