title: Lymph node metastases in rectal cancer after preoperative radiochemotherapy: impact of intramesorectal distribution and residual micrometastatic involvement.
abstract: BACKGROUND
  After neoadjuvant chemoradiation (CRT), the pathologic determined lymph node (LN) status is the most important prognostic factor in rectal cancer patients. Here we assessed the prognostic impact of residual LN micrometastases (<0.2 cm) and the intramesorectal distribution of LN metastases.
  
  
  METHODS
  Surgical specimens from 81 patients with cUICC II/III rectal cancer undergoing neoadjuvant CRT and total mesorectal excision within the German Rectal Cancer Trial CAO/ARO/AIO-04 were prospectively evaluated. The entire mesorectal compartment was paraffin embedded and screened microscopically. The number and distribution of mesorectal LN macrometastases and micrometastases were correlated with disease-free (DFS) and cancer-specific overall survival (CSS).
  
  
  RESULTS
  A total of 2412 LNs were detected (mean 29.8±13.7). Twenty-five patients had residual LN metastases (ypN+). The incidence of metastases in the peritumoral mesorectum was higher (7.7%) than that proximal to the tumor (1.5%), whereas no metastases were identified below the tumor level. Patients with both proximal and peritumoral involvement showed a significantly reduced CSS (hazard ratio=5.4; P<0.05). Fourteen patients with ypN+ status (56%) had micrometastases, 9 patients (36%) had only micrometastatic involvement. Patients with nodal macrometastases had a reduced DFS (P<0.01) and CSS (P<0.005) as compared with ypN0 patients, whereas residual micrometastases had no influence on survival.
  
  
  CONCLUSIONS
  Despite the high incidence of residual LN micrometastases they did not seem to have a prognostic impact in this series. Micrometastases might indicate responsive tumors to CRT with a more favorable biology. The intramesorectal distribution of LN metastases had a prognostic impact and should be validated in further studies.
authors.affiliation: Department of General and Visceral Surgery, University Medical Center Göttingen, Germany. tsprenger@chirurgie-goettingen.de
authors.forename: Thilo
authors.initials: T
authors.lastname: Sprenger
authors.forename: Hilka
authors.initials: H
authors.lastname: Rothe
authors.forename: Heinz
authors.initials: H
authors.lastname: Becker
authors.forename: Tim
authors.initials: T
authors.lastname: Beissbarth
authors.forename: Kia
authors.initials: K
authors.lastname: Homayounfar
authors.forename: Korbinian
authors.initials: K
authors.lastname: Gauss
authors.forename: Julia
authors.initials: J
authors.lastname: Kitz
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wolff
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Scheel
authors.forename: Michael
authors.initials: M
authors.lastname: Ghadimi
authors.forename: Claus
authors.initials: C
authors.lastname: Rödel
authors.forename: Lena-Christin
authors.initials: LC
authors.lastname: Conradi
authors.forename: Torsten
authors.initials: T
authors.lastname: Liersch
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000556:secondary* / Q000628:therapy*; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D018572:Disease-Free Survival; D005260:Female; D005858:Germany; D006801:Humans; D053208:Kaplan-Meier Estimate; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D061206:Neoplasm Micrometastasis; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D016612:Paraffin Embedding; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome