title: Does circumferential tumor location affect the circumferential resection margin status in mid and low rectal cancer?
abstract: OBJECTIVE
  The purpose of this study was to assess the impact of circumferential tumor location on circumferential resection margin (CRM) status and the depth of tumor invasion in mid and low rectal cancer.
  
  
  METHODS
  We retrospectively analyzed whole-mount slides of 58 patients who underwent total mesorectal excision for mid and low rectal cancer. The rate of tumor-positive CRM was compared according to the circumferential tumor location. In 31 patients, morphometric analyses of whole-mount specimens were performed to measure the depth of tumor invasion according to circumferential tumor location.
  
  
  RESULTS
  Among 58 patients, 50% of tumors were anterior tumor and 50% were nonanterior. A tumor-positive CRM was more observed frequently in anterior tumors than in nonanterior tumors (41.1% vs. 10.3%, p = 0.007). In a multivariate analysis, anterior tumor was the only independent risk factor for a positive CRM (odds ratio 4.725, 95% confidence interval 1.102-20.261, p = 0.037). In a morphometric analysis of 31 patients, the depth of tumor invasion from the muscularis mucosa was greater (11.9 mm vs. 6.6 mm, p = 0.028) in those with anterior tumors.
  
  
  CONCLUSIONS
  Anterior tumors are associated with a higher risk of tumor-positive CRM and tend to exhibit deeper invasion in mid and low rectal cancer.
authors.affiliation: Department of Surgery, Chuncheon Sacred Heart Hospital, Hallym University College of Medicine, Chuncheon, South Korea.
authors.forename: Byung Mo
authors.initials: BM
authors.lastname: Kang
authors.affiliation: Department of Pathology, Kyung Hee Medical Center, Kyung Hee University School of Medicine, Seoul, South Korea.
authors.forename: Yong-Koo
authors.initials: YK
authors.lastname: Park
authors.affiliation: Department of Surgery, Kyung Hee Medical Center, Kyung Hee University School of Medicine, Seoul, South Korea.
authors.forename: Sun Jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Surgery, Kyung Hee Medical Center, Kyung Hee University School of Medicine, Seoul, South Korea.
authors.forename: Kil Yeon
authors.initials: KY
authors.lastname: Lee
authors.affiliation: Department of Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, South Korea.
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Department of Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, South Korea. Electronic address: leeshdr@khu.ac.kr.
authors.forename: Suk-Hwan
authors.initials: SH
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D000072662:Margins of Excision; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: circumferential resection margin; depth of invasion; rectal cancer; tumor location