Timely tumor response analysis after preoperative chemoradiotherapy and curative surgery in locally advanced rectal cancer: A multi-institutional study for optimal surgical timing in rectal cancer

ypCR rates increased after 5 weeks and decreased after 10 weeks and the delayed (>7 weeks after CRT) group showed significantly increased ypCR rates than the early arm (⩽7 weeks after CR). The optimal timing for curative surgery in rectal cancer when tumor response is maximal is after 7 weeks and before 10 weeks following preoperative CRT.