title: Identification of patients with high-risk lymph node-negative colorectal cancer and potential benefit from adjuvant chemotherapy.
abstract: BACKGROUND
  Adjuvant chemotherapy is not indicated in lymph node-negative colorectal adenocarcinoma (CRC), even though some cases will present recurrent disease. It is important to identify a subgroup of patients with the highest risk of relapse because of the potential benefit of adjuvant chemotherapy. The objective of this study is to define the prognostic factors and describe a method for the selection of this subgroup.
  
  
  METHODS
  A retrospective cohort of 124 patients with lymph node-negative CRC with complete surgical resection was studied. Cox's proportional hazards model was used to define the prognostic factors associated with CRC-related survival and to develop a method for prediction of recurrence probability.
  
  
  RESULTS
  The cohort included 62 women and 62 men with mean age 55.8 years. The mean follow-up period was 11.7 years. T classification of the primary tumor, differentiation grade, carcinoembryonic antigen level, gender and the presence of neural invasion were significant prognostic factors according to the multivariate analysis (final model P=0.00001). Using risk ratios for these prognostic factors, we defined a high-risk group of 78 patients and a low-risk group of 46 patients with 24 and 5 recurrences, respectively (recurrence rates of 30.8% and 10.9% respectively, P=0.011).
  
  
  CONCLUSIONS
  Using these factors, a prognostic scale was developed to predict high risk of recurrence in cases of completely resected CRC and to identify them as a subgroup of patients with potential benefit of adjuvant chemotherapy.
authors.affiliation: Gastroenterology Department, Surgery Division, Instituto Nacional de Cancerología, México DF, México. lonate@prodigy.net.mx
authors.forename: Luis F
authors.initials: LF
authors.lastname: Oñate-Ocaña
authors.forename: Rene
authors.initials: R
authors.lastname: Montesdeoca
authors.forename: Carlos M
authors.initials: CM
authors.lastname: López-Graniel
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Aiello-Crocifoglio
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mondragón-Sánchez
authors.forename: Mario
authors.initials: M
authors.lastname: Cortina-Borja
authors.forename: Roberto
authors.initials: R
authors.lastname: Herrera-Goepfert
authors.forename: Cuauhtemoc
authors.initials: C
authors.lastname: Oros-Ovalle
authors.forename: Dolores
authors.initials: D
authors.lastname: Gallardo-Rincón
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D017024:Chemotherapy, Adjuvant / Q000379:methods* / Q000451:nursing*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013997:Time Factors