The circumferential resection margin was clear in 222 patients ( 93 % ) in the laparoscopic surgery group and in 228 patients ( 97 % ) in the open surgery group ( risk difference of -3.7 % [ 95 % CI , -7.6 % to 0.1 % ] ; P = .06 ) , the distal margin was clear in 236 patients ( 99 % ) in the laparoscopic surgery group and in 234 patients ( 99 % ) in the open surgery group ( risk difference of -0.4 % [ 95 % CI , -1.8 % to 1.0 % ] ; P = .67 ) , and total mesorectal excision was complete in 206 patients ( 87 % ) in the laparoscopic surgery group and 216 patients ( 92 % ) in the open surgery group ( risk difference of -5.4 % [ 95 % CI , -10.9 % to 0.2 % ] ; P = .06 ) .