title: Flattened tumor requires a more careful attention for residual distal cancer spread in locally advanced lower rectal carcinoma after chemoradiotherapy.
abstract: OBJECTIVE
  Limited data are available on distal resection margin (DRM) for lower rectal cancer (LRC) after preoperative chemoradiotherapy (pre-CRT); thus, we aimed to establish the criteria for DRMs as estimated by the macroscopic tumor appearance.
  
  
  METHODS
  This was a pathological study using whole-mount sections that included the entire circumference of tumor. Residual cancer spread located most distally from the macroscopic tumor border was mainly evaluated.
  
  
  RESULTS
  A retrospective cohort of 42 consecutive patients with locally advanced LRC after pre-CRT was enrolled, and 38 patients were eligible for this study. According to the macroscopic tumor appearance, 18 patients had raised-type and 20 had flattened-type tumors. Patients with flattened-type tumors were closely associated with histopathological regression grade. Residual distal cancer spread (RDCS) was located ≤4.0 mm (median, 0.1 mm) in the raised-type tumors and ≤17.1 mm (median, 4.2 mm) in the flattened-type tumors. RDCS in flattened-type tumors was distributed diffusely and distally from the tumor border (p = 0.022).
  
  
  CONCLUSIONS
  Even in patients evaluated as pre-CRT responders, flattened tumors often accompanied distally located residual cancer that had spread from the tumor border and require more careful attention in order to ensure cancer clearance.
authors.affiliation: Department of Surgery, Division of Digestive Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kinoshita
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Murayama
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kuriu
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Kokuba
authors.forename: Eigo
authors.initials: E
authors.lastname: Otsuji
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000601:surgery* / Q000628:therapy; D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D018365:Neoplasm, Residual; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery* / Q000628:therapy; D012007:Rectum / Q000473:pathology / Q000601:surgery*; D012189:Retrospective Studies; D016896:Treatment Outcome