How to Deal With Large Colorectal Polyps

Snare, Endoscopic Mucosal Resection, and Endoscopic Submucosal Dissection; Resect or Refer?

Selvi Thirumurthi; Gottumukkala S. Raju

Disclosures

Curr Opin Gastroenterol. 2016;32(1):26-31. 

In This Article

Abstract and Introduction

Abstract

Purpose of review The importance of accurate polyp detection and removal is paramount to preventing colon cancer. Resection of large polyps can be challenging to the endoscopist based on their size, shape, or location. Large polyps have the potential of harboring malignancy and a higher risk of complications with resection. Careful assessment of each lesion and meticulous resection using the appropriate tools and techniques is essential.

Recent findings Over the last 15 years, the development of endoscopic mucosal resection EMR) and endoscopic submucosal dissection (ESD) techniques has presented the endoscopist with the opportunity to manage patients with large and flat lesions thereby avoiding the need for surgery. However, these techniques are complex and require extensive knowledge and skill in the use of various devices to resect a lesion completely and manage bleeding and perforation associated with these procedures.

Summary Large colon polyps manifest as either polypoid or nonpolypoid (flat) lesions. Polypoid lesions, especially those with pedicles, are removed with snare resection, whereas flat lesions may require the use of EMR or ESD. Resection of large polyps (>1 cm) requires additional tools and techniques to ensure safe and complete resection. We will discuss our approach to dealing with large colorectal polyps: snare, EMR, and ESD; resect or refer?

Introduction

Endoscopic snare resection of colon polyps was introduced in the early 1970s.[1] Twenty years later, its benefits in the prevention of colon cancer are clearly documented.[2] Resection of large polyps can be challenging to the endoscopist because of the risk of complications, such as bleeding, perforation, and incomplete resection. Hence, patients with large polyps are frequently referred to surgery.[3] However, advances in endoscopic tools and techniques, such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) offer us an opportunity to manage patients with large and flat lesions and thereby avoiding the need for surgery. Here, we present recent advances in the endoscopic management of large colon polyps – how to resect these lesions using snare, EMR, or ESD and when to refer. Given the recent advances in the management of nonpolypoid lesions, we present that topic in great detail with an in depth review of advances during the last 2 years to help the readers.

Large Polypoid Lesions: Resect or Refer?

Routine use of a cap fitted high definition colonoscope helps to assess large colorectal lesions and determine their resectability.

Polyp Assessment

The Paris system allows for a standardized approach to describing the morphology of polyps and is worth including in endoscopic reporting.[4] Polyp size can be estimated using an open biopsy forceps, different sized snares, etc. Specialists in complex polypectomy are better in assessing polyp size compared with gastroenterologists, trainees, and surgeons.[5] Sessile lesions are easier to estimate compared with flat lesions.[5] Ability to measure the size of polyps accurately may allow endoscopists to determine whether to resect the lesion or refer the patient.

The risk of malignancy increases with polyp size. Lesions with high-grade dysplasia or superficial submucosal invasion without lymphovascular invasion can be cured with endoscopic resection, whereas lesions with deep submucosal invasion of cancer are at an increased risk of lymph node metastasis and postpolypectomy complications. Careful examination of the entire surface of a large polypoid lesion with narrow band imaging is critical to identify cancer.[6] Deep submucosal invasion of cancer should be recognized during optical diagnosis (i.e., darker compared with the background, disrupted, or missing blood vessels and an amorphous or absent surface pit pattern) and such lesions are best managed in referral centers.

Polyp Resection and Prevention of Complications

Resection of large polypoid colorectal lesions, especially those with pedicles, is often less complicated than resection of flat lesions that we discuss later, and can usually be accomplished safely when appropriate precautions are taken. Large polyps (>10 mm), lesions with a thick stalk, and those with more advanced histopathology carry a higher risk of postpolypectomy bleeding.[7,8] Detachable nylon loop ligation of the stalk before or after resection of a large pedunculated polyp reduces risk of bleeding. Clips can be utilized to close the resection site to decrease the risk of complications. A combination of epinephrine injection and mechanical therapy (with endoclips or nylon loops) has been shown to decrease the rates of early and delayed postpolypectomy bleeding. An excellent review by Burgess et al.[9] on colonoscopy and polypectomy covers the details of management of pedunculated polyps.

Large Nonpolypoid Lesions: Resect or Refer?

Benign lesions and early mucosal cancers with a negligible risk for concurrent lymph node metastasis are curable with complete EMR. One should look for obvious features of submucosal cancer (converging folds, chicken skin appearance, submucosal mass effect, and balding of a pedunculated polyp) and take directed biopsies from cancerous areas in the polyp to confirm the diagnosis when referring them to surgery. In patients where there are no obvious features of cancer, magnification endoscopy using dye spray and electronic chromoendoscopy to assess mucosal surface pit pattern and microvessels can help to distinguish between adenoma and carcinoma in 70–90% of cases.[10] Dysplasia in a sessile serrated polyp can be identified by changes in mucosal surface and identification of nodules.[11] Hence, it is essential to learn how to differentiate benign lesions from cancers before undertaking large polyp resections.[12] Simple random biopsies of flat lesions should be avoided because biopsies may miss the cancer in a large polyp or a flat lesion; in addition, biopsies may cause submucosal fibrosis and preclude safe and complete EMR or ESD in the future.

The decision to resect during index colonoscopy or not depends on room setup as well as the patient's plans (travel or not and their proximity to a medical facility, if a complication were to occur) after the colonoscopy. If a decision is made to refer the patient, it is preferable to avoid biopsies and place a tattoo a few centimeters distal to the lesion in the same plane as the lesion using submucosal saline bleb technique.[13] If a biopsy is required, use a pediatric forceps and take one biopsy (based on my observations in an expert ESD center in Japan).

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