Colon Polyps (Colonic Adenoma): Surgical Therapy

1st order

  • Complete ablation of the polyp/adenoma (polypectomy) during colonoscopy (colonoscopy).
    • Polyps ≤ 5 mm either ablation with biopsy forceps (forceps resection) or with cold snare (snare resection; suitable for small polyps ≤ 10 mm)
    • For larger sessile polyps, endoscopic mucosal resection (EMR) is the standard.
  • Transanal (“through the anus“) endoscopic microsurgery (TEM).
  • Partial colon resection (colon resection) – surgical removal of the adenoma-bearing portion of the colon.

Note: Prophylactic clip closure after polypectomy appears to be worthwhile for large lesions (≥ 20 mm) located in the proximal colon (essentially the ascending colon, which is located between the caecum (appendix) and the right colonic flexure (flexura coli dextra; timely bend at the colon). In these cases, the procedure reduced the risk of rebleeding.

Endoscopy and polyp management/follow-up recommendations

  • Adenoma carriers have a 40-50% risk of recurrent adenomas.
  • After ablation of serrated adenomas (SSA) in the right hemicolon, interval carcinomas occur more frequently. Interval carcinomas are carcinomas that occur between the index colonoscopy and the scheduled follow-up interval.SSA are typically > 5 mm, located in the right-sided colon, and are shallowly raised; demarcation from the surrounding area by an overlying mucinous layer
  • Risk of degeneration depends on: Histology (“fine tissue findings”), size and degree of intraepithelial neoplasia (neoplasm); highest risk of degeneration (25-40% within in 10 years) occurs with: Size > 10 mm and / or villous neoplasia and / or intraepithelial neoplasia.

Follow-up intervals

Type of lesion First control Further control
Non-neoplastic polyps
  • None
 None
Low-risk adenoma*
  • 5 years; 5-10 years [S-3 guideline].
 5 years
High-risk adenoma* *
  • 3 years (possibly shorter if > 10 adenomas).
  • If ≥ 5 adenomas of any size are detected, the follow-up interval should be <3 years [S-3 guideline].
 5 years (if initial control is unremarkable).
Histologically no complete ablation
  • 2-6 months; 6 months [S-3 guideline].
 According to type and findings in first control
Large, flat, or sessile adenomas ablated in piece-meal technique (ablated in multiple portions)
  • 2-6 months (control of ablation site).
 3 years, then 5 years

* Low-risk adenomas

  • 1-2 Adenomas, < 1 cm, tubular, low-grade IEN (dysplasias/intraepithelial neoplasms).

* * High-risk adenomas

  • ≥ 3 tubular adenomas
  • ≥ 1 adenoma ≥ 1 cm and villous architecture.
  • ≥ 1 adenoma with high-grade IEN
  • ≥ 10 serrated adenomas of any size.

However, there are from studies that recommend colonoscopy follow-up after three years for all adenoma types (2). Follow-up intervals after polypectomy [S-3 guideline].

Baseline Interval
Control colonoscopy 1 or 2 small tubular adenomas (< 1 cm) without villous component or high-grade intraepithelial neoplasia 5-10 years
3 or 4 adenomas or ≥ 1 adenoma ≥ 1 cm or villous component or high-grade intraepithelial neoplasia 3 yrs
≥ 5 adenomas <3 years
Serrated adenomas (small, flat, and raised) As in classical adenomas
Ablation in piece-meal technique Control of the ablation site after 2-6 months

Procedure for malignant polyp, so-called polyp carcinoma (T1 carcinoma)

  • The overall T1 carcinoma group has a lymph node metastasis rate of 0-20% depending on the G stage:
    • Low-risk situation (G1 or G2, no lymphatic vessel infiltration – metastasis rate of 0-4% [surgical resection may be omitted if histologic result is R0].
    • If tumor budding, i.e., histologic evidence of tumor cell clusters (≤5 cells) of dedifferentiated or isolated tumor cells at the invasion front, then this is independently considered a high-risk factor accordingly!
    • High-risk situation (G3 or G4 or lymphatic vessel invasion) – here a radical surgical treatment is required.

Further

  • Rate of colonoscopically incompletely removed colorectal polyps: 13.8% of polyps between 1 and 20 mm are incompletely resected, according to the results of the meta-analysis. In the range of 10 to 20 mm, the proportion even increases to almost 21%.
  • Polypectomy (polyp removal) for “low-risk” adenomas results in a significant risk reduction for colon carcinoma (colon cancer). This is not true for patients with “high-risk” adenomas; they continued to have an increased risk of dying from colon cancer in subsequent years compared with the general population.
  • Endoscopic resection of colon polyps 20 mm or larger in diameter is an effective and very safe intervention. Only 7.8% of endoscopically treated patients (503 of 6,442 patients) eventually required surgery in the subsequent two years. In the majority of cases, surgery was performed because of insufficient success of endoscopic treatment. Reasons for this were the presence of invasive carcinoma in 58% of cases, and precancerous lesions had not been curatively removed in 28%.Only in 31 patients was surgery performed because of side effects of the procedure.In subsequent follow-up endoscopies during the surveillance period (mean 2 years), recurrence or residual disease was detected endoscopically in 13.8%. In 1.9% of the renewed lesions, i.e. in 0.3% of all patients, it was an invasive colon carcinoma (colon cancer).
  • Nonstalked colorectal adenomas: In a meta-analysis, more than 11,000 patients with nonstalked colorectal adenomas were treated by endoscopic submucosal dissection (ESD). ESD allows large tumors to be ablated in one piece. In this regard, submucosal infiltrations of 1,000 micrometers or less are considered low malignant risk lesions for which endoscopic resection is considered curative. Lesions with an infiltration depth of 1,000 micrometers or less were found in 1,363 resections, a pooled rate of 8.0% (95% confidence interval: 6.1%-10.3%); 899 lesions (7.7%) had an infiltration depth greater than 1,000 micrometers.CONCLUSION: ESD should be used only in patients with lesions that have a high probability of an infiltration depth less than 1,000 micrometers.
  • In endoscopic resection of colonic polyps, the recurrence rate can be significantly reduced by coagulation of the sedimentation margins (thermal ablation: recurrence adenoma 5, 2%; group without therapy: recurrence rate 21%).
  • Surveillance colonoscopies/control colonoscopies after polypectomy (polyp removal) (subsequent risk groups according to the UK guideline):
    • Low-risk group: patients with 1-2 adenomas <10 mm; recommendation: control colonoscopy: after 5-10 years; 10-year incidence of colorectal cancer: 1.7% (comparable to general population); a single control colonoscopy reduced CRC risk by 44%Note: A higher risk of carcinoma was seen in patients in whom the index colonoscopy was incomplete or not certainly complete, a villous component was present, or the polyps were proximal. This collective showed a ten-year incidence without control colonoscopy of 2.1 %
    • Intermediate-risk group: patients with 3-4 adenomas < 10 mm or 1-2 adenomas, at least one of which was ≥ 10 mm; control colonoscopy: after 3 years; 10-year incidence for colorectal carcinoma: 2.6% (comparable to general population)Note: A higher risk of carcinoma was seen in patients in whom index colonoscopy was incomplete or not certainly complete, adenomas with high-grade dysplasia, or proximal polyps. This collective showed a 10-year incidence without control colonoscopy of 3.7% (versus 1.3% for low-risk, i.e., without the above risk factors).
    • High-risk group: patients with ≥ 5 adenomas < 10 mm or ≥ 3 adenomas ≥ 10 mm; control colonoscopy: after 3 years; 10-year incidence for colorectal cancer without control colonoscopy: 5.7% CRC; with one colonoscopy, 5.6%; two control colonoscopies halved the CRC rate at the population level.