title: Prognostic value of perineural invasion in patients with stage II colorectal cancer.
abstract: BACKGROUND
  Perineural invasion (PNI) may influence the prognosis after resection of colorectal cancer (CRC); whether this is a definite prognostic factor remains controversial. This study determined the clinicopathologic factors associated with oncologic outcome after radical resection of stage II CRC, focusing on PNI.
  
  
  METHODS
  We retrospectively reviewed 341 consecutive patients who underwent curative surgery for stage II CRC between January 2001 and December 2006. Of these, 278 patients (81.5%) received postoperative 5-fluorouracil-based chemotherapy. The oncologic outcomes and the risk factors for recurrence were analyzed.
  
  
  RESULTS
  PNI was detected in 57 of 341 patients (16.7%) and was significantly associated with depth of tumor invasion (P = .035) and positive lymphovascular invasion (P < .001). Multivariate analyses revealed that PNI was a significant independent prognostic factor for disease-free survival, not for overall survival. With a median follow-up period of 57.6 months, the 5-year disease-free and overall survival rates of the patients were 80.2 and 82.6%, respectively. The 5-year disease-free survival of the PNI-negative group was significantly higher than that of the PNI-positive group (P < .001). Within the PNI-positive patients, those receiving chemotherapy had significantly higher 5-year disease-free survival than the others (P = .023).
  
  
  CONCLUSIONS
  This study illustrates the value of PNI as a prognostic factor for stage II CRC. Moreover, PNI-positive patients should be considered for postoperative chemotherapy.
authors.affiliation: Department of Surgery, Chonnam National University Hwasun Hospital and Medical School, Gwangju, Korea.
authors.forename: Jung Wook
authors.initials: JW
authors.lastname: Huh
authors.forename: Hyeong Rok
authors.initials: HR
authors.lastname: Kim
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017024:Chemotherapy, Adjuvant; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D010525:Peripheral Nerves / Q000473:pathology*; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D005472:Fluorouracil