Colon polyps overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]
Overview
Historical Perspective
In 1895, the first sigmoidoscopy was developed to visualize the colon. Since then, it has been used to screen for colon polyps and colorectal cancer. In 1975, it was reported that adenomas are the precursors of colorectal cancer and hyperplastic polyps are non-neoplastic lesions. Since 1992, different pathways of polyp-cancer have been introduced, including molecular adenoma-carcinoma progression, mutator phenotype, serrated (neoplasia) pathway.
Classification
Colon polyps may be classified into two groups of neoplastic and nonneoplastic. Non-neoplastic polyps consist of inflammatory and hamartomatous polyps. Neoplastic polyps consist of serrated and adenomatous polyps. Adenomatous polyps may be classified into several subtypes based on endoscopic, histologic features and degree of dysplasia. Adenomas may be classified according to endoscopic features into four groups including sessile, pedunculated, flat, or depressed. Adenomas may be classified according to histologic features into three groups including tubular, tubulovillous, and villous.
Pathophysiology
Causes
The cause of colon polyps has not been identified.
Differentiating Colon Polyps from Other Diseases
Colon polyps might present solitary or multiple. Solitary colon polyps usually have no symptoms. Colon polyps must be differentiated from other genetic diseases that cause multiple polyps, such as Peutz–Jeghers syndrome, Cowden syndrome, Bannayan–Riley–Ruvalcaba syndrome, juvenile polyposis, and McCune–Albright syndrome.
Epidemiology and Demographics
The exact incidence and prevalence of colon polyps are unknown. Colon polyps are incidentally found in colonoscopies and sigmoidoscopies. However, the incidence of colon polyps is estimated to be 200,000 cases in the united states annually. The prevalence of colon polyps is between 10-25% in different screening studies. The incidence of colon polyps increases with age; the median age at diagnosis is 50 years. Colon polyps usually affect individuals of the African American race. Men are more commonly affected by colon polyps than women. Colon polyps is a common disease worldwide.
Risk Factors
Risk factors in the development of colon polyps may be environmental, genetic, and lifestyle behaviors. The most potent risk factor in the development of colon polyps is age. Other risk factors include family history, obesity, cigarette smoking, and alcohol consumption.
Screening
There is insufficient evidence to recommend routine screening for colon polyps. According to the guidelines screening for the colon polyps must be done earlier after the first colon polyps are discovered. Hyperplastic polyps have no malignant tendency and recommendation for the colonoscopy is similar to general population. Adenomatous and serrated polyps have neoplastic nature and must be followed every 3-5 years.
Natural History, Complications, and Prognosis
Diagnosis
Diagnostic Study of Choice
Colonoscopy and flexible sigmoidoscopy are diagnostic studies of choice to diagnose colon polyps.