title: Use of medications to reduce risk for primary breast cancer: a systematic review for the U.S. Preventive Services Task Force.
abstract: BACKGROUND
  Medications to reduce risk for primary breast cancer are recommended for women at increased risk; however, use is low.
  
  
  OBJECTIVE
  To update evidence about the effectiveness and adverse effects of medications to reduce breast cancer risk, patient use of such medications, and methods for identifying women at increased risk for breast cancer.
  
  
  METHODS
  MEDLINE and Cochrane databases (through 5 December 2012), Scopus, Web of Science, clinical trial registries, and reference lists.
  
  
  METHODS
  English-language randomized trials of medication effectiveness and adverse effects, observational studies of adverse effects and patient use, and diagnostic accuracy studies of risk assessment.
  
  
  METHODS
  Investigators independently extracted data on participants, study design, analysis, follow-up, and results, and a second investigator confirmed key data. Investigators independently dual-rated study quality and applicability using established criteria.
  
  
  RESULTS
  Seven good- and fair-quality trials indicated that tamoxifen and raloxifene reduced incidence of invasive breast cancer by 7 to 9 cases in 1000 women over 5 years compared with placebo. New results from STAR (Study of Tamoxifen and Raloxifene) showed that tamoxifen reduced breast cancer incidence more than raloxifene by 5 cases in 1000 women. Neither reduced breast cancer-specific or all-cause mortality rates. Both reduced the incidence of fractures, but tamoxifen increased the incidence of thromboembolic events more than raloxifene by 4 cases in 1000 women. Tamoxifen increased the incidence of endometrial cancer and cataracts compared with placebo and raloxifene. Trials provided limited and heterogeneous data on medication adherence and persistence. Many women do not take tamoxifen because of associated harms. Thirteen risk-stratification models were modest predictors of breast cancer.
  
  
  CONCLUSIONS
  Data on mortality and adherence measures and for women who are nonwhite, are premenopausal, or have comorbid conditions were lacking.
  
  
  CONCLUSIONS
  Medications reduced the incidence of invasive breast cancer and fractures and increased the incidence of thromboembolic events. Tamoxifen was more effective than raloxifene but also increased the incidence of endometrial cancer and cataracts. Use is limited by adverse effects and inaccurate methods to identify candidates.
  
  
  BACKGROUND
  Agency for Healthcare Research and Quality.
authors.affiliation: Pacific Northwest Evidence-based Practice Center, Oregon Health & Science University, Mailcode BICC, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239-3098, USA. nelsonh@ohsu.edu
authors.forename: Heidi D
authors.initials: HD
authors.lastname: Nelson
authors.forename: M E Beth
authors.initials: ME
authors.lastname: Smith
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Griffin
authors.forename: Rongwei
authors.initials: R
authors.lastname: Fu
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000517:prevention & control*; D002386:Cataract / Q000139:chemically induced; D016889:Endometrial Neoplasms / Q000139:chemically induced; D005260:Female; D050723:Fractures, Bone / Q000139:chemically induced; D006801:Humans; D055118:Medication Adherence; D010358:Patient Participation; D020849:Raloxifene Hydrochloride / Q000009:adverse effects / Q000627:therapeutic use*; D018570:Risk Assessment; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use*; D013923:Thromboembolism / Q000139:chemically induced; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen; D020849:Raloxifene Hydrochloride