title: Evaluation of chemoresponse assays as predictive markers.
abstract: BACKGROUND
  A chemoresponse assay that can be used to predict which patients will respond to which drugs would be useful in directing treatment. Two new analytic methods to assess the predictive ability of a chemoresponse assay have been proposed by Tian et al.
  
  
  METHODS
  Three examples in which a hypothetical assay has no predictive ability are considered to evaluate the properties of the proposed analytic methods.
  
  
  RESULTS
  For these specific examples, the proposed methods incorrectly suggest that the assay is predictive.
  
  
  CONCLUSIONS
  The examples presented here demonstrate that it can be challenging to evaluate the predictive value of a chemoresponse assay.
authors.affiliation: Biometric Research Branch, MSC 9735, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Korn
authors.affiliation: Biometric Research Branch, MSC 9735, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: B
authors.initials: B
authors.lastname: Freidlin
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D054316:Biomarkers, Pharmacological / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D016555:Matched-Pair Analysis; D009369:Neoplasms / Q000175:diagnosis* / Q000188:drug therapy* / Q000453:epidemiology; D011237:Predictive Value of Tests; D011379:Prognosis; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D054316:Biomarkers, Pharmacological; D014408:Biomarkers, Tumor