Staging of rectal cancer after polypectomy: usefulness of endorectal US.

Abstract

To determine the usefulness of endorectal ultrasonography (US) in staging rectal cancer discovered at polypectomy. Before surgical resection, endorectal US was performed in 18 consecutive patients with adenocarcinoma discovered in polypectomy specimens. A rotating 7-10-MHz endoprobe with an inflatable balloon was used in all cases. The precise depth of penetration (T stage) was determined with endorectal US and correlated with the histopathologic findings. For detection of residual tumor after polypectomy, endorectal US had a sensitivity of 100%, specificity of 44%, positive predictive value of 64%, and negative predictive value of 100%. Although the precise T stage was correctly predicted with endorectal US in only eight patients (44%), endorectal US was able to demonstrate whether the tumor was limited to the bowel wall in 16 patients (89%). Endorectal US is an accurate technique for localizing tumors to or beyond the rectal wall in patients who have undergone diagnostic polypectomy. Although inaccuracies in determining the specific T stage may occur, endorectal US facilitates surgical planning in the vast majority of patients and should therefore remain the local staging technique of choice in this specific patient population.