title: Adjuvant endocrine therapy for early breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline.
abstract: BACKGROUND
  Cancer Care Ontario's Program in Evidence-Based Care (pebc) recently created an evidence-based consensus guideline on the systemic treatment of early breast cancer. The evidence for the guideline was compiled using a systematic review to answer the question "What is the optimal systemic therapy for patients with early-stage, operable breast cancer, when patient and disease factors are considered?" The question was addressed in three parts: cytotoxic chemotherapy, endocrine treatment, and her2 (human epidermal growth factor receptor 2)-targeted therapy.
  
  
  METHODS
  For the systematic review, the literature in the medline and embase databases was searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major oncology guideline organizations were also searched. The basic search terms were "breast cancer" and "systemic therapy" (chemotherapy, endocrine therapy, targeted agents, ovarian suppression), and results were limited to randomized controlled trials (rcts), guidelines, systematic reviews, and meta-analyses.
  
  
  RESULTS
  Several hundred documents that met the inclusion criteria were retrieved. Meta-analyses from the Early Breast Cancer Trialists' Collaborative Group encompassed many of the rcts found. Several additional studies that met the inclusion criteria were retained, as were other guidelines and systematic reviews.
  
  
  CONCLUSIONS
  The results of the systematic review constitute a comprehensive compilation of high-level evidence, which was the basis for the 2014 pebc guideline on systemic therapy for early breast cancer. The review of the evidence for systemic endocrine therapy (adjuvant tamoxifen, aromatase inhibitors, and ovarian ablation and suppression) is presented here; the evidence for chemotherapy and her2-targeted treatment-and the final clinical practice recommendations-are presented separately in this supplement.
authors.affiliation: Durham Regional Cancer Centre, Oshawa, ON.
authors.forename: O C
authors.initials: OC
authors.lastname: Freedman
authors.affiliation: Program in Evidence-Based Care, Cancer Care Ontario; and Department of Oncology, McMaster University, Hamilton, ON.
authors.forename: G G
authors.initials: GG
authors.lastname: Fletcher
authors.affiliation: Sunnybrook Health Science Centre, Toronto, ON.
authors.forename: S
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Cancer Centre of Southeastern Ontario, Kinston General Hospital, and Queen's University, Kingston, ON.
authors.forename: M
authors.initials: M
authors.lastname: Mates
authors.affiliation: The Ottawa Hospital Cancer Centre and University of Ottawa, Ottawa, ON.
authors.forename: S F
authors.initials: SF
authors.lastname: Dent
authors.affiliation: Durham Regional Cancer Centre, Oshawa, ON.
authors.forename: M E
authors.initials: ME
authors.lastname: Trudeau
authors.affiliation: Durham Regional Cancer Centre, Oshawa, ON.
authors.forename: A
authors.initials: A
authors.lastname: Eisen
keywords: Early breast cancer; aromatase inhibitors; endocrine therapy; hormonal therapy; hormone receptor–positive breast cancer; ovarian ablation; ovarian suppression; tamoxifen
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