Risk factors for metastases from a cancer arising in an adenomatous polyp:
(1) poorly differentiated adenocarcinoma
(2) presence of lymphatic invasion
(3) sessile polyp with invasion into the submucosa of the bowel wall
Risk factors for recurrence of a cancer arising in an adenomatous polyp:
(1) tumor present at the resection margin or very close (<= 1 mm).
where:
• Invasion of the submucosa of a pedunculated polyp (beyond the muscularis mucosae) is problematic when any of the above conditions are present.
• Some surgeons prefer a margin >= 1 cm between the advancing edge of the tumor and the resection margin. This may be hard to achieve with a small pedunculated polyp. No matter what measurement is chosen, there are always cases with distances > 1 mm which are management dilemmas.
Management:
(1) For a patient with a significant risk of metastasis or residual tumor, segmental colonic resection is recommended.
(2) For the patient with in-situ disease or a low risk of metastatic disease, then close monitoring is usually sufficient. The risk of surgery may outweigh the benefit if the risk of metastasis is low.
where:
• The final decision is usually influenced by the patient preferences and concerns in consultation with the surgeon's experience and expertise.
