AN EXAMINATION OF WHY SASKATCHEWAN WOMEN CHOOSE MASTECTOMY VERSUS BREAST CONSERVATION THERAPY IN EARLY STAGE BREAST CANCER

Introduction and Research Purpose Breast cancer is the most commonly diagnosed cancer in North America and the second most common cause of cancer death in women. For early stage breast cancer (ESBC), it is well established that breast conservation therapy (BCT) and mastectomy are equivalent treatments for survival. Treatment for ESBC can therefore be viewed as preference sensitive care, where decision-making between treatment options should vary according to patient preferences. In Canada, interprovincial mastectomy rates vary greatly from 25% to 68% between provinces with a national average of 38%. Saskatchewan has consistently reported the nation’s second highest mastectomy rate with the latest report showing 63%. There has been international research investigating why women choose mastectomy versus BCT, but there is limited data within Canada to explain these provincial variations. The aim of my thesis is to better understand Saskatchewan women’s choice between mastectomy and BCT in ESBC. In this dissertation, I have addressed the research objectives through four manuscripts outlined below Manuscript 1: To assess the current evidence, we conducted the first systematic review on the factors influencing women’s choice of mastectomy versus BCT in ESBC. Manuscript 2: To identify the factors that influence Saskatchewan women’s choice between BCT or mastectomy in ESBC, we conducted a province-based qualitative study which identified themes and subthemes influencing therapy choice. This was the first part of an exploratory mixed methods study. Manuscript 3: To help improve our understanding and organize our research, we created a conceptual framework of why women choose mastectomy versus BCT in ESBC. This framework was important in organizing our systematic review and guiding our survey. Manuscript 4: Finally, to understand decision-making influences of Saskatchewan women with ESBC, we conducted a province wide survey. Creation of this survey was grounded on our previous work and the second portion of our mixed methods study. Results and Conclusion Our research demonstrates treatment choices for Saskatchewan women with ESBC were primarily influenced by disease stage and individual belief factors. These findings would suggest that women are making their treatment choices predominantly based on individual values and preferences. The use of mastectomy and BCT rates as an indicator of quality of care may be misleading. Instead, a shift in attention towards patient-centred care is more appropriate