Fig. 1. Traditional APE and extralevator APE.

A. Traditional APE: Dotted line indicates dissection plane. Because levator muscle is not included in surgical specimen, it is appropriate for tumors without threatening to levator muscle plane. B. Extralevator APE: Tumor infiltration extends to left levator ani muscle. Levators are removed in this surgical specimen. This type of surgery is mandatory for lower rectal cancer with levator involvement to achieve negative pCRM. APE = abdominoperineal excision, pCRM = pathologic circumferential resection margin