title: Endocrine therapy initiation, discontinuation and adherence and breast imaging among 21-gene recurrence score assay-eligible women under age 65.
abstract: Aside from chemotherapy utilization, limited data are available on the relationship between gene expression profiling (GEP) testing and breast cancer care. We assessed the relationship between GEP testing and additional variables and the outcomes of endocrine therapy initiation, discontinuation and adherence, and breast imaging exams in women under age 65 years.
  
  
  
  Data from five state cancer registries were linked with claims data and GEP results. We assessed variables associated with survivorship care outcomes in an incident cohort of 5014 commercially insured women under age 65 years, newly diagnosed with stage I or II hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2) non-positive breast cancer from 2006 to 2010.
  
  
  
  Among tested women, those with high Oncotype DX® Breast Recurrence Score® (RS) were significantly less likely to initiate endocrine therapy than women with low RS tumors (OR 0.40 (95% CI 0.20 to 0.81); P = 0.01). Among all test-eligible women, receipt of Oncotype DX testing was associated with a greater likelihood of endocrine therapy initiation (OR 2.48 (95% CI 2.03 to 3.04); P <0.0001). The odds of initiation were also significantly higher for tested vs. untested women among women who did not initiate chemotherapy within six months of diagnosis (OR 3.25 (95% CI 2.53 to 4.16)), with no effect in women who received chemotherapy. Discontinuation and adherence and breast imaging exams were unrelated to tested status or RS.
  
  
  
  Lower endocrine therapy initiation rates among women with high RS tumors and among untested women not receiving chemotherapy are concerning, given its established efficacy. Additional research is needed to suggest mechanisms to close this gap.
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA. sco4@georgetown.edu.
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: O'Neill
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA.
authors.forename: Claudine
authors.initials: C
authors.lastname: Isaacs
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA.
authors.forename: Filipa
authors.initials: F
authors.lastname: Lynce
authors.affiliation: Hackensack Meridian Health, Hackensack, NJ, USA.
authors.forename: Deena Mary Atieh
authors.initials: DM
authors.lastname: Graham
authors.affiliation: Genomic Health, Inc, Redwood City, CA, USA.
authors.forename: Calvin
authors.initials: C
authors.lastname: Chao
authors.affiliation: School of Medicine Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: Vanessa B
authors.initials: VB
authors.lastname: Sheppard
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA.
authors.forename: Yingjun
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: HealthCore, Inc, Wilmington, DE, USA.
authors.forename: Chunfu
authors.initials: C
authors.lastname: Liu
authors.affiliation: IMS Health, Fairfax, VA, USA.
authors.forename: Nandini
authors.initials: N
authors.lastname: Selvam
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Schwartz
authors.affiliation: Georgetown Lombardi Comprehensive Cancer Center, 3300 Whitehaven Street, NW, Suite 4100, Washington, DC, 20007, USA.
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Potosky
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality; D017024:Chemotherapy, Adjuvant; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D053208:Kaplan-Meier Estimate; D055118:Medication Adherence; D008875:Middle Aged; D009367:Neoplasm Staging; D016017:Odds Ratio; D012008:Recurrence; D012307:Risk Factors; D055815:Young Adult
keywords: Breast cancer; Breast imaging; Endocrine therapy; Gene expression profiling; Genomic testing