title: Predicting women's intentions for contralateral prophylactic mastectomy: An application of an extended theory of planned behaviour.
abstract: OBJECTIVE
  Most women with unilateral breast cancer (BC) without BRCA1/2 gene mutations are at low risk of contralateral breast cancer (CBC). One CBC risk-management option is contralateral prophylactic mastectomy (CPM). While there is no evidence that CPM increases life-expectancy, its uptake is increasing. This study aimed to assess the validity of an extended social-cognition model, the Theory of Planned Behaviour (TPB), in predicting women's intentions to undergo CPM.
  
  
  METHODS
  Four hundred women previously treated for BC completed an online survey exploring demographic and disease factors, attitude, subjective norm, perceived behavioural control, anticipated regret, uncertainty avoidance, self-efficacy to not have CPM and intentions to undergo CPM in a common hypothetical decision-making scenario.
  
  
  RESULTS
  The TPB uniquely explained 25.7% of intention variance. Greater anticipated regret, uncertainty avoidance and lower self-efficacy to cope with not having CPM were associated with stronger CPM intentions, explaining an additional 7.7%, 10.6% and 2.9% respectively, of variance over and above the TPB. Women who had undergone CPM, had not attended university, and had children reported stronger CPM intentions.
  
  
  CONCLUSIONS
  A holistic understanding of CPM decision-making appears to require consideration beyond CBC risk, demographics and disease characteristics, exploring women's expectations about CPM outcomes, others' opinions, and avoidance of emotionality and difficulties associated with not undergoing surgery. This study provides a theoretical basis from which the complexity of CPM decision-making may be understood, and from which resources for patients and treating staff may be developed to support women's informed decision-making aligning with their personal values.
authors.affiliation: School of Psychology, Griffith Taylor Building (A19), The University of Sydney, NSW 2006, Australia. Electronic address: iric5786@uni.sydney.edu.au.
authors.forename: Imogen
authors.initials: I
authors.lastname: Richards
authors.affiliation: School of Psychology, Griffith Taylor Building (A19), The University of Sydney, NSW 2006, Australia.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Tesson
authors.affiliation: Department of Oncology, Auckland City Hospital, 2 Park Road, Grafton, Auckland 1023, New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Porter
authors.affiliation: Division of Cancer Medicine, Peter MacCallum Cancer Centre, Melbourne, Australia; Sir Peter MacCallum Dept. of Oncology, Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, School of Population and Global Health, Locked Bag 1, A'Beckett Street, VIC 8006, Australia; Department of Medicine, St Vincent's Hospital, The University of Melbourne, Level 4, Clinical Sciences Building, 29 Regent St, Fitzroy, VIC 3065, Australia.
authors.forename: Kelly-Anne
authors.initials: KA
authors.lastname: Phillips
authors.affiliation: Sydney Catalyst, Level 6, Chris O'Brien Lifehouse Building (C39Z), Sydney, NSW 2006, Australia.
authors.forename: Nicole
authors.initials: N
authors.lastname: Rankin
authors.affiliation: University of Western Australia (M507), 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Toni
authors.initials: T
authors.lastname: Musiello
authors.affiliation: Breast Cancer Network Australia, 293 Camberwell Rd, Camberwell, VIC 3124, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Marven
authors.affiliation: School of Psychology, Griffith Taylor Building (A19), The University of Sydney, NSW 2006, Australia; Centre for Medical Psychology & Evidence-based Decision Making/Psycho-oncology Co-operative Research Group, Level 6, Chris O'Brien Lifehouse Building (C39Z), Sydney, NSW 2006, Australia.
authors.forename: Phyllis
authors.initials: P
authors.lastname: Butow
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000517:prevention & control* / Q000523:psychology; D003430:Cross-Sectional Studies; D003657:Decision Making; D004644:Emotions; D005260:Female; D006801:Humans; D033182:Intention; D008875:Middle Aged; D000072036:Prophylactic Mastectomy; D020377:Self Efficacy; D012959:Socioeconomic Factors
keywords: Breast cancer; Contralateral breast cancer; Contralateral prophylactic mastectomy; Decision-making; Theory of planned behaviour