Poster Presentation Clinical Oncology Society of Australia 2014 Annual Scientific Meeting

Applying social-cognition models to understand women’s hypothetical intentions for Contralateral Prophylactic Mastectomy (#414)

Phyllis Butow 1 , imogen Richards 2 , Stephanie Tesson 2 , David Porter 3 , Kelly-Anne Phillips 4 , Toni Musiello 5 6 , Nicole Rankin 7 , Michelle Marven 8
  1. CeMPED/ PoCoG, The University of Sydney, NSW, Australia
  2. School of Psychology, University of Sydney, Sydney, NSW, Australia
  3. Dept of Oncology, Aukland Hospital, Aukland, New Zealand
  4. Dept of Medical Oncology, Peter McCallum Cancer Centre, Melbourne, VIC, Australia
  5. University of Western Australia, Perth, WA, Australia
  6. University of Western Australia, Perth, WA, Australia
  7. Sydney Catalyst, University of Sydney, Sydney, NSW, Australia
  8. Breast Cancer Network of Australia (BCNA), Sydney, NSW, Australia

Aims: Women with unilateral breast cancer (BC) without BRCA1/2-mutations face increased risk of contralateral breast cancer (CBC), albeit low (0.50-0.75% annually). Contralateral Prophylactic Mastectomy (CPM) reduces CBC risk by >90%, and its uptake is increasing. Yet CPM may not increase life-expectancy in low-risk women, necessitating exploration of factors influencing CPM decision-making. This study assessed the validity of the Theory of Planned Behaviour (TPB) and Protection Motivation Theory (PMT) to predict low-risk BC patients’ hypothetical CPM intentions.

Methods: Women were recruited through Breast Cancer Network Australia’s research database, comprising 2,229 women. Eligibility criteria included i) BRCA1/2-mutation negative, ii) aged 18-70 years, iii) diagnosed within 10 years prior, iv) completed primary treatment. A sample of 127 was required for sufficient power. Participants responded to an online survey eliciting demographic / disease characteristics, and TPB/PMT items pertaining to a common hypothetical CPM decision-making scenario.

Results: 400 women consented, and 368 completed the survey. Participants’ mean age was 53 years (SD=8.15). 102 women (26%) had undergone CPM, and 12% also had reconstruction. All women who had CPM and 9% who had not, discussed it with their surgeon, and 30% who had CPM and 9% who had not, discussed it with an oncologist. CPM discussions were predominantly patient-initiated (75%). Main reasons cited for having CPM were CBC risk-reduction (79%), breast symmetry (56%) and mortality risk-reduction (49%). TPB variables (attitudes, subjective norms, perceived behavioural control) and most PMT variables (self-efficacy, response-efficacy, costs, severity) correlated highly with hypothetical CPM intentions (r=.24-.58, all p<0.01), as did anticipated regret, uncertainty attitudes, screening self-efficacy and fear of recurrence (|r|=.24-.92, all p<0.01).

Conclusions: CPMappears patient-driven, with few women gaining other than surgical perspectives on risk management. Women may be over-estimating risk reduction offered by CPM. Social-cognitive and emotional variables need to be considered to holistically understand this complex decision.