Poster Presentation COSA-IPOS Joint Scientific Meeting 2012

Patient preferences for adjuvant radiotherapy in early breast cancer – an Australian sub-study of the International TARGIT trial. (#419)

Tammy Corica 1 2 , Anna K Nowak 1 , Christobel M Saunders 3 , Max K Bulsara 4 , David J Joseph 2 5
  1. School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
  2. Radiation Oncology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  3. School of Surgery and Pathology, University of Western Australia, Perth, Western Australia, Australia
  4. Institute of Health and Rehabilitation Research, University of Notre Dame, Perth, Western Australia, Australia
  5. School of Surgery and Pathology, University of Western Australia, Perth, Australia

Background
The TARGIT trial compares single dose intra-operative radiotherapy (IORT) with 6-7 week external-beam radiotherapy (EBRT) in women with early breast cancer (EBC) at low risk of local recurrence (LR). We hypothesize that IORT will give a non-inferior risk of LR compared with EBRT. In order to guide women and doctors making choices about radiotherapy, a Patient Preference study was performed to determine what increased risk of LR, without detriment to survival, women with EBC would accept, in return for the increased convenience of IORT.
Methods
A cross-sectional study of patient preferences and their determinants in 209 women who had radiotherapy on the TARGIT trial (108 had IORT and 101 had EBRT). Preferences were determined by a self-rated questionnaire using validated trade-off methodology. Disease, treatment, and demographic details were collected and quality of life during radiotherapy.
Results
While 36% of patients were prepared to accept a 4%-6% increase in LR risk for the increased convenience of IORT, 22% would not accept IORT at all. Multivariate Poisson regression identified treatment received as the only significant determinant of preferences (p<0.0001). This is despite significant differences found in two-sample Kolmogorov-Smirnov tests of quality of life scores during treatment all favouring IORT. Comparison of the treatment groups found that 60% of IORT patients would accept IORT at an increased risk of 4%-6% in contrast to 12% of patients in the EBRT group. Only 2% of IORT patients indicated they would not have IORT at all, in contrast to 43% of EBRT patients.
Conclusion
The EBRT group were risk-averse, whilst patients who had IORT valued the convenience of IORT highly. Participants of this study have justified the treatment they were randomly allocated to, which questions the validity of post-treatment patient preference studies. Further research targeting patients who have not yet received radiotherapy will now follow.