title: A high preoperative carbohydrate antigen 19-9 level is a risk factor for recurrence in stage II colorectal cancer.
abstract: BACKGROUND
  Many risk factors for recurrence in stage II colorectal cancer (CRC) have been proposed, and the efficacy of adjuvant chemotherapy is still controversial. This study aimed to identify risk factors for tumor recurrence and assess whether they are related to the benefits of adjuvant chemotherapy in stage II CRC.
  
  
  METHODS
  Patients with stage II CRC that was curatively operated on in a tertiary hospital between 2005 and 2014 were analyzed. Cox's proportional hazards models were applied to identify risk factors for recurrence and overall mortality. Kaplan-Meier methods were used to evaluate whether adjuvant chemotherapy was beneficial in terms of recurrence-free survival (RFS).
  
  
  RESULTS
  A total of 384 patients were identified, among whom 38 (10%) received adjuvant chemotherapy. In a median follow-up of 48.6 months, 52 patients (14%) developed recurrence. Multivariate analyses identified two independent parameters that significantly decreased RFS; pathological T4 [hazard ratio (HR), 2.34; 95% confidence interval (CI), 1.31-4.15; p = .0045) and preoperative carbohydrate antigen (CA) 19-9 > 37 U/ml (HR 1.96; 95% CI 1.02-3.58; p = .045). These factors also inversely correlated with overall survival; T4: HR 2.10, p = .019) and CA 19-9 > 37 U/ml (HR 2.15, p = .025). The combination of T4 and CA 19-9 > 37 U/ml resulted in an increased HR (3.52) for recurrence. However, adjuvant chemotherapy did not improve RFS in patients with these features.
  
  
  CONCLUSIONS
  The present study demonstrated elevated CA 19-9 levels as well as T4 independently predicted worse long-term outcomes in patients with stage II CRC. However, the characterization of patients who gain survival advantages by adjuvant chemotherapy requires further investigation.
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nozawa
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Ishihara
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Kawai
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hata
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Tomomichi
authors.initials: T
authors.lastname: Kiyomatsu
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishikawa
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Otani
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Yasuda
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Murono
authors.affiliation: a Department of Surgical Oncology , The University of Tokyo , Tokyo , Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D018395:CA-19-9 Antigen / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D011300:Preoperative Care; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen