title: Surgical lateral clearance in resected rectal carcinomas. A multivariate analysis of clinicopathologic features.
abstract: BACKGROUND
  Incomplete removal of the tumor is the main cause of local recurrence in rectal carcinomas; this often occurs at the lateral aspects devoid of the peritoneum. The authors examined prospectively 80 resected rectal carcinoma specimens in an attempt to discover a reliable method to detect lateral resection margin (LRM) involvement by these tumors and to identify pathologic factors that would be prognostically important.
  
  
  METHODS
  In each of the 80 resected specimens, the whole tumor was embedded, and whole-mount sections of the entire tumor and the surrounding mesorectum were examined after serial transverse slicing. The distance from the outermost part of the tumor to the LRM (surgical clearance) was measured.
  
  
  RESULTS
  Six (7.5%) of the 80 specimens showed LRM involvement (defined as surgical clearance < or = 1 mm) in the single slice seen macroscopically to have the deepest tumor invasion, whereas 16 specimens (20%) were found to have LRM involved after examining all slices microscopically. Surgically clearance had a strong inverse relationship with Dukes staging (P < 0.001) and depth of tumor invasion (P = 0.001). The overall local recurrence rate was 28%; it was much higher (53%) in the patients who had LRM involved by tumor. As a whole, local recurrence was related significantly to LRM involvement (P = 0.006). Survival rates were correlated with macroscopic (n = 3) and microscopic (n = 13) features of the resected specimens using Cox multivariate regression analysis. Three of the nine pathologic parameters isolated (i.e., surgical clearance, cellular differentiation, and number of involved pericolic lymph nodes) were identified as favorable independent prognostic factors.
  
  
  CONCLUSIONS
  Local recurrence is related closely to LRM involvement. Embedding and examining the entire tumor and mesorectum is the only reliable and satisfactory means of assessing LRM. Detailed pathologic study on the resected tumor is important when assessing the prognosis.
authors.affiliation: Department of Pathology, University of Hong Kong.
authors.forename: I O
authors.initials: IO
authors.lastname: Ng
authors.forename: I S
authors.initials: IS
authors.lastname: Luk
authors.forename: S T
authors.initials: ST
authors.lastname: Yuen
authors.forename: P W
authors.initials: PW
authors.lastname: Lau
authors.forename: C J
authors.initials: CJ
authors.lastname: Pritchett
authors.forename: M
authors.initials: M
authors.lastname: Ng
authors.forename: G P
authors.initials: GP
authors.lastname: Poon
authors.forename: J
authors.initials: J
authors.lastname: Ho
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate