Management of the malignant polyp

Abstract

In the United States, the prevalence of adenomatous polyps found during colonoscopic evaluation ranges from 25 to 41%, and of these, 2 to 5% contain invasive malignancy. The management of the malignant polyp continues to be challenging. Endoscopic resection by polypectomy has been shown to be sufficient for management of certain polyps containing cancer; however, it is important to keep in mind that polypectomy does not remove the lymph node drainage basin and may be an inadequate resection for some adenocarcinoma containing polyps that have specific histologic features. Depth of invasion has been shown to correlate with the risk of lymph node metastasis. Other unfavorable histologic features include lymphovascular invasion, poor differentiation, inability to assess margin (piecemeal resection), and positive resection margin (< 2 mm); these are important factors to consider in management. For these patients formal oncologic surgical resection is indicated. Traditional open or laparoscopic procedures are routinely used for colectomy in these patients. Following polypectomy or segmental colectomy, surveillance of these patients is critical, and can lead to excellent long-term outcomes.

Keywords: Haggitt level; Malignant polyp; adenocarcinoma; adenomatous polyp; endoscopic polypectomy; segmental colectomy.

Figure 1

Anatomic landmarks of pedunculated and sessile malignant polyps with respect to Haggitt level. Adapted from Haggitt et al.

Figure 2

Depth of submucosal invasion in sessile malignant polyps. Sm₁, invasion into upper third; Sm₂, invasion into middle third; Sm₃, invasion into lower third. Adapted from Kudo.