title: Serum protein profiling using an aptamer array predicts clinical outcomes of stage IIA colon cancer: A leave-one-out crossvalidation.
abstract: BACKGROUND
  In this study, we established and validated a model for predicting prognosis of stage IIA colon cancer patients based on expression profiles of aptamers in serum.
  
  
  METHODS
  Bloods samples were collected from 227 consecutive patients with pathologic T3N0M0 (stage IIA) colon cancer. We incubated 1,149 serum molecule-binding aptamer pools of clinical significance with serum from patients to obtain aptamers bound to serum molecules, which were then amplified and marked. Oligonucleotide arrays were constructed with the base sequences of the 1,149 aptamers, and the marked products identified above were reacted with one another to produce profiles of the aptamers bound to serum molecules. These profiles were organized into low- and high-risk groups of colon cancer patients based on clinical information for the serum samples. Cox proportional hazards model and leave-one-out cross-validation (LOOCV) were used to evaluate predictive performance.
  
  
  RESULTS
  During a median follow-up period of 5 years, 29 of the 227 patients (11.9%) experienced recurrence. There were 212 patients (93.4%) in the low-risk group and 15 patients (6.6%) in the high-risk group in our aptamer prognosis model. Postoperative recurrence significantly correlated with age and aptamer risk stratification (p = 0.046 and p = 0.001, respectively). In multivariate analysis, aptamer risk stratification (p < 0.001) was an independent predictor of recurrence. Disease-free survival curves calculated according to aptamer risk level predicted through a LOOCV procedure and age showed significant differences (p < 0.001 from permutations).
  
  
  CONCLUSIONS
  Aptamer risk stratification can be a valuable prognostic factor in stage II colon cancer patients.
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jung Wook
authors.initials: JW
authors.lastname: Huh
authors.affiliation: Biois Corp, Seoul, Korea.
authors.forename: Sung Chun
authors.initials: SC
authors.lastname: Kim
authors.affiliation: Biostatistics and Clinical Epidemiology Center, Samsung Medical Center, Seoul, Korea.
authors.forename: Insuk
authors.initials: I
authors.lastname: Sohn
authors.affiliation: Biostatistics and Clinical Epidemiology Center, Samsung Medical Center, Seoul, Korea.|Department of Biostatistics and Bioinformatics, Duke University, Durham, NC, USA.
authors.forename: Sin-Ho
authors.initials: SH
authors.lastname: Jung
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Hee Cheol
authors.initials: HC
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D052157:Aptamers, Nucleotide / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood; D003110:Colonic Neoplasms / Q000097:blood* / Q000401:mortality / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis
chemical_list: D052157:Aptamers, Nucleotide; D014408:Biomarkers, Tumor
keywords: aptamer; colon cancer; prognosis