title: Lymph node retrieval after preoperative chemoradiotherapy for rectal cancer.
abstract: BACKGROUND
  Current guidelines recommend the assessment of at least 12 lymph nodes for rectal cancer staging. Preoperative chemoradiotherapy may affect lymph node yield in this malignancy. This study investigated the impact of neoadjuvant chemoradiotherapy on the number of lymph nodes retrieved from rectal cancer patients.
  
  
  METHODS
  An analysis of 162 rectal cancer patients who underwent curative surgery between 2005 and 2010. Seventy-one patients with stage II or III tumors received preoperative chemoradiotherapy. Using multivariate analysis, we assessed the correlation between clinicopathologic variables and number of retrieved lymph nodes. We also evaluated the association between survival and number of lymph nodes obtained.
  
  
  RESULTS
  On multivariate analysis, preoperative chemoradiotherapy was the only variable to independently affect the number of lymph nodes obtained. The mean number of lymph nodes was 14.2 in patients treated with preoperative chemoradiotherapy and 19.4 in those not treated (P < 0.001). In the chemoradiotherapy group, 29.6 % of patients had fewer than 12 lymph nodes obtained compared with 9.9 % in the primary surgery group (P = 0.003). After chemoradiation, the number of retrieved lymph nodes was inversely correlated with tumor regression grade. Results showed that 5-year overall and disease-free survival were similar whether the patient had 12 or more nodes retrieved or not.
  
  
  CONCLUSIONS
  Preoperative chemoradiotherapy reduces the lymph node yield in rectal cancer. The number of retrieved lymph nodes is affected by degree of histopathologic response of the tumor to chemoradiation. Thus, number of lymph nodes should not be used as a surrogate for oncologic adequacy of resection after neoadjuvant chemoradiotherapy for rectal cancer.
authors.affiliation: Division of Coloproctology, Hospital de Clinicas de Porto Alegre, and Department of Surgery, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. damin@terra.com.br
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Damin
authors.forename: Mário A
authors.initials: MA
authors.lastname: Rosito
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Contu
authors.forename: Cláudio
authors.initials: C
authors.lastname: Tarta
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Ferreira
authors.forename: Lucia M
authors.initials: LM
authors.lastname: Kliemann
authors.forename: Gilberto
authors.initials: G
authors.lastname: Schwartsmann
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D008197:Lymph Node Excision / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D012007:Rectum / Q000601:surgery*; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil