title: The influence of the treatment response on the impact of resection margin status after preoperative chemoradiotherapy in locally advanced rectal cancer.
abstract: BACKGROUND
  Circumferential resection margin (CRM) and distal resection margin (DRM) have different impact on clinical outcomes after preoperative chemoradiotherapy (CRT) followed by surgery. Effect and adequate length of resection margin as well as impact of treatment response after preoperative CRT was evaluated.
  
  
  METHODS
  Total of 403 patients with rectal cancer underwent preoperative CRT followed by total mesorectal excision between January 2004 and December 2010. After applying the criterion of margin less than 0.5 cm for CRM or less than 1 cm for DRM, 151 cases with locally advanced rectal cancer were included as a study cohort. All patients underwent conventionally fractionated radiation with radiation dose over 50 Gy and concurrent chemotherapy with 5-fluorouracil or capecitabine. Postoperative chemotherapy was administered to 142 patients (94.0%). Median follow-up duration was 43.1 months.
  
  
  RESULTS
  The 5-year overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS) rates, and locoregional control rates (LRC) were 84.5%, 72.8%, 74.2%, and 86.3%, respectively. CRM of 1.5 mm and DRM of 7 mm were cutting points showing maximal difference in a maximally selected rank method. In univariate analysis, CRM of 1.5 mm was significantly related with worse clinical outcomes, whereas DRM of 7 mm was not. In multivariate analysis, CRM of 1.5 mm, and ypN were prognosticators for all studied endpoints. However, CRM was not a significant prognostic factor for good responders, defined as patients with near total regression or T down-staging, which was found in 16.5% and 40.5% among studied patients, respectively. In contrast, poor responders demonstrated a significant difference according to the CRM status for all studied end-points.
  
  
  CONCLUSIONS
  Close CRM, defined as 1.5 mm, was a significant prognosticator, but the impact was only prominent for poor responders in subgroup analysis. Postoperative treatment strategy may be individualized based on this finding. However, findings from this study need to be validated with larger cohort.
authors.forename: Joo Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea. ekchie93@snu.ac.kr.
authors.forename: Eui Kyu
authors.initials: EK
authors.lastname: Chie
authors.forename: Kyubo
authors.initials: K
authors.lastname: Kim
authors.forename: Seung-Yong
authors.initials: SY
authors.lastname: Jeong
authors.forename: Kyu Joo
authors.initials: KJ
authors.lastname: Park
authors.forename: Jae-Gahb
authors.initials: JG
authors.lastname: Park
authors.forename: Gyeong Hoon
authors.initials: GH
authors.lastname: Kang
authors.forename: Sae-Won
authors.initials: SW
authors.lastname: Han
authors.forename: Do-Youn
authors.initials: DY
authors.lastname: Oh
authors.forename: Seock-Ah
authors.initials: SA
authors.lastname: Im
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
authors.forename: Yung-Jue
authors.initials: YJ
authors.lastname: Bang
authors.forename: Sung W
authors.initials: SW
authors.lastname: Ha
mesh_terms: D000328:Adult; D000368:Aged; D059248:Chemoradiotherapy; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery* / Q000628:therapy; D016896:Treatment Outcome