title: Factors affecting uptake and adherence to breast cancer chemoprevention: a systematic review and meta-analysis.
abstract: BACKGROUND
  Preventive therapy is a risk reduction option for women who have an increased risk of breast cancer. The effectiveness of preventive therapy to reduce breast cancer incidence depends on adequate levels of uptake and adherence to therapy. We aimed to systematically review articles reporting uptake and adherence to therapeutic agents to prevent breast cancer among women at increased risk, and identify the psychological, clinical and demographic factors affecting these outcomes.
  
  
  METHODS
  Searches were carried out in PubMed, CINAHL, EMBASE and PsychInfo, yielding 3851 unique articles. Title, abstract and full text screening left 53 articles, and a further 4 studies were identified from reference lists, giving a total of 57. This review was prospectively registered with PROSPERO (CRD42014014957).
  
  
  RESULTS
  Twenty-four articles reporting 26 studies of uptake in 21 423 women were included in a meta-analysis. The pooled uptake estimate was 16.3% [95% confidence interval (CI) 13.6-19.0], with high heterogeneity (I(2) = 98.9%, P < 0.001). Uptake was unaffected by study location or agent, but was significantly higher in trials [25.2% (95% CI 18.3-32.2)] than in non-trial settings [8.7% (95% CI 6.8-10.9)] (P < 0.001). Factors associated with higher uptake included having an abnormal biopsy, a physician recommendation, higher objective risk, fewer side-effect or trial concerns, and older age. Adherence (day-to-day use or persistence) over the first year was adequate. However, only one study reported a persistence of ≥ 80% by 5 years. Factors associated with lower adherence included allocation to tamoxifen (versus placebo or raloxifene), depression, smoking and older age. Risk of breast cancer was discussed in all qualitative studies.
  
  
  CONCLUSIONS
  Uptake of therapeutic agents for the prevention of breast cancer is low, and long-term persistence is often insufficient for women to experience the full preventive effect. Uptake is higher in trials, suggesting further work should focus on implementing preventive therapy within routine care.
authors.affiliation: Wolfson Institute of Preventive Medicine, Queen Mary University of London, London Health Behaviour Research Centre, University College London, London, UK sam.smith@qmul.ac.uk.
authors.forename: S G
authors.initials: SG
authors.lastname: Smith
authors.affiliation: Wolfson Institute of Preventive Medicine, Queen Mary University of London, London.
authors.forename: I
authors.initials: I
authors.lastname: Sestak
authors.affiliation: Health Behaviour Research Centre, University College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Forster
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, USA.
authors.forename: A
authors.initials: A
authors.lastname: Partridge
authors.affiliation: Institute for Women's Health, University College London, London, UK.
authors.forename: L
authors.initials: L
authors.lastname: Side
authors.affiliation: Division of General Internal Medicine, Northwestern University, Chicago, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Wolf
authors.affiliation: Centre for Behavioural Medicine, University College London, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Horne
authors.affiliation: Health Behaviour Research Centre, University College London, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Wardle
authors.affiliation: Wolfson Institute of Preventive Medicine, Queen Mary University of London, London.
authors.forename: J
authors.initials: J
authors.lastname: Cuzick
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control*; D018890:Chemoprevention / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D020849:Raloxifene Hydrochloride / Q000009:adverse effects / Q000627:therapeutic use; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D013629:Tamoxifen; D020849:Raloxifene Hydrochloride
keywords: adherence; chemoprevention; decision-making; medication; preventive therapy; uptake