Approach

Removal of polyps significantly reduces the risk of death from colorectal cancer.[55][56][57]

Polyps are removed for histological examination to exclude malignancy and/or to manage polyp-associated symptoms or complications. Endoscopic resection of non-malignant polyps is preferred to surgical resection, where possible, because it is associated with lower morbidity and mortality.[58]

Large broad-based polyps, or those situated in anatomically inaccessible areas, are usually unsuitable for endoscopic resection and require open or laparoscopic bowel resection.[59]

Polypectomy techniques

Endoscopic polypectomy is usually performed by simple snare excision or by 'hot biopsy' (in which monopolar diathermy is used to excise the polyp and simultaneously coagulate its base).

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) utilise saline injections to lift the area of mucosa to be resected, followed by resection of the mucosa and upper submucosa using either suction and a snare or a submucosal resection device. [Figure caption and citation for the preceding image starts]: Colonic adenoma pre-excisionFrom the personal collection of Dr G. Malietzis; used with permission [Citation ends].com.bmj.content.model.Caption@15cbc222[Figure caption and citation for the preceding image starts]: Post-polypectomyFrom the personal collection of Dr G. Malietzis; used with permission [Citation ends].com.bmj.content.model.Caption@2f46819c These are particularly useful if the polyp is sessile (flat) rather than pedunculated (with a stalk). The effectiveness of EMR and ESD for treating large colorectal polyps has been confirmed by systematic reviews.[60][61] 

Polyps that do not rise easily with submucosal saline or hyaluronidase infiltration are highly suspicious for invasive malignancy. Successful endoscopic mucosal resection is unlikely if three or more quadrants do not rise easily with fluid infiltration; surgical management is more suitable in these cases.

Surgical polypectomy may be required if a polyp is very low in the rectum and its distal margin cannot be safely endoscopically resected. Small polyps (up to 8 mm) may be removed using a cold snare technique where electrocautery is not required. This technique has confirmed efficacy.[62]

Management of polyps with invasive cancer

Polyps are considered malignant if cancer invades through the muscularis mucosa into the submucosa. Carcinoma in situ is not considered malignant because it is unable to metastasise to regional lymph nodes.[63]

Management of polyps containing invasive cancer depends on the type of polyp and the presence or absence of favourable histological features.[63]

Favourable histological features are:[63][64]

  • Well-differentiated or moderately differentiated (grade 1 or 2) adenocarcinoma

  • No angiolymphatic invasion

  • Negative margin of resection.

Surgery is not required for patients with completely resected pedunculated polyps with favourable histological features.[63]

Patients with completely resected sessile polyps with favourable histological features may be considered for observation or for colectomy with en bloc removal of regional lymph nodes.[63] Patients with sessile polyps may have increased risk of disease recurrence, mortality, and metastases compared with patients with pedunculated polyps.[65]

See Colorectal cancer for further details on surgery for invasive colorectal cancer.

If a specimen is fragmented, resection margins cannot be assessed, or there are unfavourable histological features, the patient should undergo further investigations to assess the extent of disease prior to colectomy with en bloc removal of regional lymph nodes.​[63]

See Colorectal cancer for further detail on the investigation and management of such patients.

Surveillance after polypectomy

Surveillance after polypectomy is individualised to the patient's risk of colorectal cancer. Colorectal cancer risk is determined by the presence, number, and size of polyps found at index colonoscopy, as well as by factors such as age and family history.

The US Multi-Society Task Force on Colorectal Cancer recommends that patients with 1 to 2 small (<1 cm) low-grade tubular adenomas should undergo repeat colonoscopy in 5 to 10 years.[66] Finding 3 to 10 adenomas, or any adenoma ≥1 cm, displaying high-grade dysplasia, or with villous features, should prompt repeat colonoscopy at 3 years; >10 adenomas at a single examination should prompt follow-up in <3 years and a familial syndrome should be considered.[66] Sessile adenomas removed piecemeal should be reviewed within 1 year to ensure complete removal.[66] The US National Comprehensive Cancer Network guidelines recommend colonoscopy 6 months after piecemeal resection; the European Society for Gastroenterology recommends colonoscopy at 3-6 months for any piecemeal endoscopic resection of polyps ≥2 cm.​[47][67]​

People with high-risk adenomas have a three- to fourfold higher risk of incident colorectal cancer during follow-up, compared with people with no adenomas or low-risk adenomas.[49]

UK guidelines state that if two or more pre-malignant polyps (including at least one advanced colorectal polyp) or five or more pre-malignant polyps are found, the patient should undergo a one-off surveillance colonoscopy at 3 years.[45]

If a patient has had invasive adenocarcinoma in a polyp that was completely excised, colonoscopy is recommended 1 year after index colonoscopy.[63] If an advanced adenoma (villous polyp, polyp >10 mm, or high-grade dysplasia) is present, colonoscopy should be repeated after 1 year. If there is no advanced adenoma, colonoscopy is recommended at 3 years, and then every 5 years.[63]

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