title: Assessing the potential cost-effectiveness of retesting IHC0, IHC1+, or FISH-negative early stage breast cancer patients for HER2 status.
abstract: BACKGROUND
  Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) tests are commonly used to assess human epidermal growth factor 2 (HER2) status of tumors in patients with breast cancer. This analysis evaluates the likely cost-effectiveness of expanded retesting to assess HER2 tumor status in women with early stage breast cancer.
  
  
  METHODS
  We developed a decision-analytic model to estimate the incremental cost-effectiveness ratio (ICER) of expanded reflex testing from a US payer perspective. Expanded reflex testing is defined as retesting tumor specimens from patients whose tumors are IHC0, IHC1+, or FISH-negative on their first test. In the base case, we assumed that 80% of patient tumors are initially IHC-tested and 20% are FISH-tested. Testing outcomes for IHC and FISH with and without retesting were based on published meta-analyses. The cost of tests and treatment and the long-term health outcomes were obtained from the literature.
  
  
  RESULTS
  In the base case, we estimated that 2.27% of women who received expanded reflex testing would be HER2-positive and receive trastuzumab treatment: the projected ICER was $36,721 per life year or $39,745 per quality-adjusted life year (QALY). This varied between $47,100 per QALY and $35,500 per QALY if we assumed that 1%-8% of patients retested were then HER2+, respectively. The results of deterministic and probabilistic sensitivity analysis were robust. This strategy would result in 4700 (2000-17,000) patients being eligible to receive trastuzumab treatment annually.
  
  
  CONCLUSIONS
  Retesting patients who are IHC0, IHC1+, or FISH-negative is projected to be a cost-effective clinical strategy.
authors.affiliation: VeriTech Corporation, Mercer Island, Washington; University of Washington, Seattle, Washington.
authors.forename: Louis P
authors.initials: LP
authors.lastname: Garrison
authors.forename: Deepa
authors.initials: D
authors.lastname: Lalla
authors.forename: Melissa
authors.initials: M
authors.lastname: Brammer
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Babigumira
authors.forename: Bruce
authors.initials: B
authors.lastname: Wang
authors.forename: Edith A
authors.initials: EA
authors.lastname: Perez
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000191:economics* / Q000378:metabolism / Q000473:pathology; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D005188:False Negative Reactions; D005260:Female; D017048:Health Care Costs; D006801:Humans; D007150:Immunohistochemistry / Q000191:economics*; D017404:In Situ Hybridization, Fluorescence / Q000191:economics*; D008875:Middle Aged; D009367:Neoplasm Staging; D010342:Patient Acceptance of Health Care; D019057:Quality-Adjusted Life Years; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D012680:Sensitivity and Specificity; D000068878:Trastuzumab; D014481:United States
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C508053:ERBB2 protein, human
keywords: HER2; HER2 testing; Herceptin; adjuvant; cost-effectiveness; cost-utility; early breast cancer; economics; pharmacoeconomics; trastuzumab