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.
The definite surgical timing in rectal cancer after preoperative chemoradiotherapy (CRT) has not yet been fully examined. We assess the tumor response and identify the optimal operation timing after preoperative CRT in rectal cancer.



The study included data of 1786 patients with locally advanced rectal cancer (cT3-4N0-2M0). They received preoperative CRT followed by total mesorectal excision. Total radiation dose was 50.4Gy in 28 fractions. Interval time between preoperative CRT and surgery ranged from 2 to 26weeks, with a median interval of 7.2weeks. Primary endpoint was to evaluate the period of highest downstaging and pathological complete response (ypCR) rates to determine the optimal timing for curative surgery after CRT.



Downstaging rates peaked between 6 and 7weeks after CRT and declined afterward. ypCR rates increased from 5 to 6weeks after CRT and decreased after 9 to 10weeks. Downstaging rates were similar between the two arms showing 36.9% in the early arm (⩽7weeks) and 37.0% in the delayed arm (>7weeks). ypCR rates were significantly higher in the delayed arm, as compared to the early arm (12.3% vs. 8.6%, p=0.011). The delayed arm had higher sphincter preservation rates than the early arm with a marginal significance (92.4% vs. 89.9%, p=0.078). There was no statistically significant difference regarding relapse-free survival and overall survival between the two arms.



ypCR rates increased after 5weeks and decreased after 10weeks and the delayed (>7weeks after CRT) group showed significantly increased ypCR rates than the early arm (⩽7weeks after CR). The optimal timing for curative surgery in rectal cancer when tumor response is maximal is after 7weeks and before 10weeks following preoperative CRT.
Center for Colorectal Cancer, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
Yoo-Kang
YK
Kwak
Department of Radiation Oncology, Seoul National University College of Medicine, Republic of Korea; Department of Radiation Oncology, Ewha Womans University School of Medicine, Republic of Korea.
Kyubo
K
Kim
Center for Colorectal Cancer, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea. Electronic address: koppul@catholic.ac.kr.
Jong Hoon
JH
Lee
Center for Colorectal Cancer, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
Sung Hwan
SH
Kim
Center for Colorectal Cancer, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
Hyeon Min
HM
Cho
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Dae Yong
DY
Kim
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Tae Hyun
TH
Kim
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Sun Young
SY
Kim
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Ji Yeon
JY
Baek
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Jae Hwan
JH
Oh
Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Republic of Korea.
Taek Keun
TK
Nam
Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Republic of Korea.
Mee Sun
MS
Yoon
Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Republic of Korea.
Jae Uk
JU
Jeong
Department of Radiation Oncology, Seoul National University College of Medicine, Republic of Korea.
Eui Kyu
EK
Chie
Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Suwon, Republic of Korea.
Hong Seok
HS
Jang
Department of Radiation Oncology, Seoul National University Bundang Hospital, College of Medicine, Bundang, Republic of Korea.
Jae Sung
JS
Kim
D000328:Adult; D000368:Aged; D059248:Chemoradiotherapy / Q000379:methods; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000401:mortality / Q000628:therapy*
Chemoradiotherapy; Rectal cancer; Response; Surgery; Timing