A. Colonoscopic Polypectomy
Most adenomatous and serrated polyps are less than 2 cm in size, and are readily amenable to colonoscopic removal; this can be done with biopsy forceps (for those less than 3 mm), with cold snare excision (for those less than 8–10 mm), or with snare cautery (for those 10–20 mm). Sessile polyps larger than 2 cm may be removed by appropriately trained physicians using a variety of endoscopic techniques (eg, saline-lift mucosal resection or dissection) or infrequently may require surgical resection. Patients with large sessile polyps removed in piecemeal fashion should undergo repeated colonoscopy in 2–6 months to verify complete polyp removal. Complications after colonoscopic polypectomy include perforation in 0.2% and clinically significant bleeding in 0.3–1.0% of all patients, but 2–8% following mucosal resection of large lesions.
A malignant polyp is an adenoma that appears grossly benign at endoscopy but on histologic assessment is found to contain cancer that has penetrated through the muscularis mucosae into the submucosa. Malignant polyps may be considered to be adequately treated by polypectomy alone if: (1) the polyp is completely excised and submitted for pathologic examination, (2) it is well differentiated, (3) the margin is not involved, and (4) there is no vascular invasion. The risk of residual cancer or nodal metastasis with favorable histologic features is less than 1%. The excision site of these "favorable" malignant polyps should be checked in 3 months for residual tissue. In patients with malignant polyps that have unfavorable histologic features, cancer resection is advisable if the patient is a good operative candidate.
B. Postpolypectomy Surveillance
Adenomas and serrated polyps can be found in 30–40% of patients when another colonoscopy is performed within 3–5 years after the initial examination and polyp removal. Periodic colonoscopic surveillance is therefore recommended to detect these “metachronous” lesions, which either may be new or may have been overlooked during the initial examination. Most of these polyps are small, without high-risk features, and of little immediate clinical significance. The probability of detecting advanced neoplasms at surveillance colonoscopy depends on the number, size, and histologic features of the polyps removed on initial (index) colonoscopy. Current guidelines recommend that patients with 1–2 tubular adenomas smaller than 1 cm (without villous features or high-grade dysplasia) should have their next colonoscopy in 5–10 years. Patients with 3–10 adenomas, an adenoma larger than 1 cm, or an adenoma with villous features or high-grade dysplasia should have their next colonoscopy at 3 years. Patients with more than 10 adenomas should have a repeat colonoscopy at 1–2 years and may be considered for evaluation for a familial polyposis syndrome. Surveillance colonoscopy at 5 years is appropriate for patients with small (less than 1 cm) serrated polyps without cytologic dysplasia; surveillance colonoscopy at 3 years should be considered for serrated polyps larger than 1 cm and those with cytologic atypia. No surveillance is recommended for patients with small, typical hyperplastic polyps located in the distal colon and rectum.
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