Local excision after polypectomy for rectal polyp cancer: when is it worthwhile?

The optimal management of a polyp cancer that has been removed endoscopically is unclear. Further local excision is often advocated to remove the polyp stalk or scar or to ensure clear margins, but the benefit of this is unclear. The aim of this paper is to determine whether the indications for further local excision can be better defined.

Data were collected from two institutions (in UK and Denmark) which maintain prospective databases to collect information on all patients undergoing transanal endoscopic microsurgery (TEM). The study group was all patients who had a TEM after macroscopically complete polypectomy for rectal cancer. Data covering an 11-year period were analysed.

Sixty three patients had TEM with no residual cancer after macroscopically complete polypectomy. Residual adenoma was found in 23 (37%). A postpolypectomy endoscopy had not detected the residual adenoma in three. Malignant local recurrence occurred in five patients (8%) and distant metastases in another two (3%). Recurrence occurred in 4/23 (17%) when there was residual adenoma in the TEM specimen and in 3/40 (7.5%) where there was scar only, although this did not reach significance. In two instances recurrence was around 10 years after TEM. Those with residual adenoma at TEM tended to have poorer survival.

Further local excision often reveals no residual cancer despite microscopically involved polypectomy margins. Careful endoscopy is required to assess the polypectomy site as residual tumour can be missed. In the absence of residual adenoma, TEM does not appear to be of benefit, although a small risk of recurrence exists.