title: Influence of unrecognized molecular heterogeneity on randomized clinical trials.
abstract: OBJECTIVE
  In solid tumor oncology, decisions regarding treatment and eligibility for trials are governed by histologic diagnosis. Despite this reliance on histology and the assumption that histology defines the disease, underlying molecular heterogeneity likely differentiates among patients' outcomes.
  
  
  METHODS
  To illustrate how unrecognized molecular heterogeneity might obscure a truly effective new therapy for cancer, we analyzed the planning assumptions and results of a hypothetical randomized controlled trial of chemoradiotherapy for a cancer found to be drug sensitive in preliminary phase II studies.
  
  
  RESULTS
  Randomized controlled trials of effective cancer therapies can be falsely negative if therapeutic benefit is overestimated during study design because of enrichment of phase II trials for treatment-sensitive subtypes, a beneficial effect in responding patients is diluted by large numbers of nonresponding patients, or a beneficial effect in responders is reversed by a negative effect in nonresponders.
  
  
  CONCLUSIONS
  Molecular heterogeneity, if it confers different risks to patients and is unaccounted for in the design of a randomized study, can result in a clinical trial that is underpowered and fails to detect a truly effective new therapy for cancer.
authors: Department of Biostatistics, Harvard School of Public Health, 655 Huntington Avenue, Boston, MA 02115, USA. betensky@hsps.harvard.edu
authors: Rebecca A
authors: RA
authors: Betensky
authors: David N
authors: DN
authors: Louis
authors: J Gregory
authors: JG
authors: Cairncross
mesh_terms: D015982:Bias; D004351:Drug Resistance; D005188:False Negative Reactions; D018740:Genetic Heterogeneity; D006801:Humans; D008967:Molecular Biology; D025202:Molecular Diagnostic Techniques; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000532:radiotherapy*; D010684:Philosophy; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D012044:Regression Analysis; D016896:Treatment Outcome