This prospective study was designed to compare the quality of life after sphincter saving surgery and abdominoperineal resection. Because of ethical issues, it is difficult to conduct as a randomized trial. On the basis of tumor location, extent, and preoperative anal function, patient will be attributed to two different operative method groups. On the assumption that 10% of the patients are lost to follow-up at 1 year, at least 74 patients undergoing APR and 220 patients undergoing SPS will be recruited. The study will be continued until the target sample size will be achieved.