title: Pathological study of distal mesorectal cancer spread to determine a proper distal resection margin.
abstract: OBJECTIVE
  Local recurrence after curative surgical resection for rectal cancer remains a major problem. Several studies have shown that incomplete removal of cancer deposits in the distal mesorectum contributes a great share to this dismal result. Clinicopathologic examination of distal mesorectum in lower rectal cancer was performed in the present study to assess the incidence and extent of distal mesorectal spread and to determine an optimal distal resection margin in sphincter-saving procedure.
  
  
  METHODS
  We prospectively examined sepecimens from 45 patients with lower rectal cancer who underwent curative surgery. Large-mount sections were performed to microscopically observe the distal mesorectal spread and to measure the extent of distal spread. Tissue shrinkage ratio was also considered. Patients with involvement in the distal mesorectum were compared with those without involvement with regard to clinicopathologic features.
  
  
  RESULTS
  Mesorectal cancer spread was observed in 21 patients (46.7%), 8 of them (17.8%) had distal mesorectal spread. Overall, distal intramural and/or mesorectal spreads were observed in 10 patients (22.2%) and the maximum extent of distal spread in situ was 12 mm and 36 mm respectively. Eight patients with distal mesorectal spread showed a significantly higher rate of lymph node metastasis compared with the other 37 patients without distal mesorectal spread (P = 0.043).
  
  
  CONCLUSIONS
  Distal mesorectal spread invariably occurs in advanced rectal cancer and has a significant relationship with lymph node metastasis. Distal resection margin of 1.5 cm for the rectal wall and 4 cm for the distal mesorectum is proper to those patients who are arranged to receive operation with a curative sphincter-saving procedure for lower rectal cancer.
authors.affiliation: Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China.
authors.forename: Gao-Ping
authors.initials: GP
authors.lastname: Zhao
authors.forename: Zong-Guang
authors.initials: ZG
authors.lastname: Zhou
authors.forename: Wen-Zhang
authors.initials: WZ
authors.lastname: Lei
authors.forename: Yong-Yang
authors.initials: YY
authors.lastname: Yu
authors.forename: Cun
authors.initials: C
authors.lastname: Wang
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Zheng
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000473:pathology* / Q000601:surgery*; D012007:Rectum / Q000473:pathology*; D016896:Treatment Outcome