title: Endocrine therapy use among elderly hormone receptor-positive breast cancer patients enrolled in Medicare Part D.
abstract: BACKGROUND
  Clinical guidelines recommend that women with hormone-receptor positive breast cancer receive  endocrine therapy (selective estrogen receptor modulators [SERMs] or aromatase inhibitors [AIs]) for five years following  diagnosis.
  
  
  OBJECTIVE
  To examine utilization and adherence to therapy for SERMs and AIs in Medicare Part D prescription  drug plans.
  
  
  METHODS
  Linked Surveillance, Epidemiology, and End Results (SEER)-Medicare data.
  
  
  METHODS
  We identified  15,542 elderly women diagnosed with hormone-receptor positive breast cancer in years 2003-2005 (the latest SEER data at  the time of the study) and enrolled in a Part D plan in 2006 or 2007 (the initial years of Part D). This permitted us to  compare utilization and adherence to therapy at various points within the recommended five-year timeframe for endocrine  therapy. SERM and AI use was measured from claim records. Non-adherence to therapy was defined as a medication possession  ratio of less than 80 percent.
  
  
  RESULTS
  Between May 2006 and December 2007, 22 percent of beneficiaries received  SERM, 52 percent AI, and 26 percent received neither. The percent receiving any endocrine therapy decreased with time from  diagnosis. Among SERM and AI users, 20-30 percent were non-adherent to therapy; out-of-pocket costs were higher for AI than  SERM and were strongly associated with non-adherence. For AI users without a low income subsidy, adherence to therapy  deteriorated after reaching the Part D coverage gap.
  
  
  CONCLUSIONS
  Many elderly breast cancer patients were not receiving  therapy for the recommended five years following diagnosis. Choosing a Part D plan that minimizes out-of-pocket costs is  critical to ensuring beneficiary access to essential medications.
authors.affiliation: US Department of Health and Human Services, Centers for Medicare & Medicaid Services, Baltimore, MD 21244, USA. gerald.riley@cms.hhs.gov
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Riley
authors.forename: Joan L
authors.initials: JL
authors.lastname: Warren
authors.forename: Linda C
authors.initials: LC
authors.lastname: Harlan
authors.forename: Steven A
authors.initials: SA
authors.lastname: Blackwell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D047072:Aromatase Inhibitors / Q000191:economics / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000191:economics / Q000453:epidemiology; D017047:Cost Sharing / Q000191:economics / Q000706:statistics & numerical data; D016527:Drug Costs / Q000706:statistics & numerical data; D005260:Female; D005382:Financing, Personal / Q000191:economics / Q000706:statistics & numerical data; D006801:Humans; D054524:Medicare Part D / Q000706:statistics & numerical data*; D020845:Selective Estrogen Receptor Modulators / Q000191:economics / Q000627:therapeutic use*; D014481:United States / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D047072:Aromatase Inhibitors; D020845:Selective Estrogen Receptor Modulators