Abdominoperineal Resection (APR) is a surgical procedure used to treat low-lying rectal cancer (carcinoma). It involves removing the rectum, anus, and part of the colon through two incisions: one in the abdomen and one in the perineum (the area between the anus and genitals). After the surgery, the patient will need a permanent colostomy, which is an opening in the abdomen where waste is collected in a bag.