title: Prediction of pathologic staging with magnetic resonance imaging after preoperative chemoradiotherapy in rectal cancer: pooled analysis of KROG 10-01 and 11-02.
abstract: OBJECTIVE
  The reported overall accuracy of MRI in predicting the pathologic stage of nonirradiated rectal cancer is high. However, the role of MRI in restaging rectal tumors after neoadjuvant CRT is contentious. Thus, we evaluate the accuracy of restaging magnetic resonance imaging (MRI) for rectal cancer patients who receive preoperative chemoradiotherapy (CRT).
  
  
  METHODS
  We analyzed 150 patients with locally advanced rectal cancer (T3-4N0-2) who had received preoperative CRT. Pre-CRT MRI was performed for local tumor and nodal staging. All patients underwent restaging MRI followed by total mesorectal excision after the end of radiotherapy. The primary endpoint of the present study was to estimate the accuracy of post-CRT MRI as compared with pathologic staging.
  
  
  RESULTS
  Pathologic T classification matched the post-CRT MRI findings in 97 (64.7%) of 150 patients. 36 (24.0%) of 150 patients were overstaged in T classification, and the concordance degree was moderate (k=0.33, p<0.01). Pathologic N classification matched the post-CRI MRI findings in 85 (56.6%) of 150 patients. 54 (36.0%) of 150 patients were overstaged in N classification. 26 patients achieved downstaging (ycT0-2N0) on restaging MRI after CRT. 23 (88.5%) of 26 patients who had been downstaged on MRI after CRT were confirmed on the pathological staging, and the concordance degree was good (k=0.72, p<0.01).
  
  
  CONCLUSIONS
  Restaging MRI has low accuracy for the prediction of the pathologic T and N classifications in rectal cancer patients who received preoperative CRT. The diagnostic accuracy of restaging MRI is relatively high in rectal cancer patients who achieved clinical downstaging after CRT.
authors.affiliation: Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea; Department of Radiation Oncology, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Jong Hoon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea.
authors.forename: Hong Seok
authors.initials: HS
authors.lastname: Jang
authors.affiliation: Department of Colorectal Surgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea.
authors.forename: Jun-Gi
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Medical Oncology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea.
authors.forename: Myung Ah
authors.initials: MA
authors.lastname: Lee
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Dae Yong
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Jae Hwan
authors.initials: JH
authors.lastname: Oh
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Sung Chan
authors.initials: SC
authors.lastname: Park
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Go-Yang, Republic of Korea.
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Baek
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hee Chul
authors.initials: HC
authors.lastname: Park
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hee Cheol
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Chonnam National University Hospital, Republic of Korea.
authors.forename: Taek-Keun
authors.initials: TK
authors.lastname: Nam
authors.affiliation: Department of Radiation Oncology, Seoul National University College of Medicine, Republic of Korea.
authors.forename: Eui Kyu
authors.initials: EK
authors.lastname: Chie
authors.affiliation: Department of Hospital Pathology, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Ji-Han
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Department of Colorectal Surgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea. Electronic address: stoh@catholic.ac.kr.
authors.forename: Seong Taek
authors.initials: ST
authors.lastname: Oh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D000069287:Capecitabine; D059248:Chemoradiotherapy / Q000379:methods*; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D009367:Neoplasm Staging; D011300:Preoperative Care / Q000379:methods; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000473:pathology / Q000628:therapy*; D012680:Sensitivity and Specificity
chemical_list: D003841:Deoxycytidine; D000069287:Capecitabine; D005472:Fluorouracil
keywords: MR imaging; Preoperative chemoradiotherapy; Rectal cancer; Restaging; Total mesorectal excision