1. Description of fracture with endocrine therapy use in older breast cancer survivors in a population-based setting Taryn Becker 123, Geoff Anderson 123, Thiwanka Wijeratne 123, Lorraine Lipscombe 123, Andrea Gruneir 123, Ophira Ginsburg 123, Amy Finch 13, Paula Rochon 123 1. Women’s College Research Institute 2. Institute for Clinical Evaluative Sciences 3. University of Toronto MethodsPreliminary Results Work in Progress Acknowledgements It is standard practice to treat postmenopausal women with localized hormone-receptor positive breast cancer with adjuvant hormone therapy (HT) While tamoxifen had been the mainstay of therapy, there is increasing evidence to support aromatase inhibitor (AI) use as the preferred treatment The 5 year survival among early breast cancer patients is greater than 87% Increased survival underscores the importance of monitoring for, preventing and treating long term unintended outcomes of HT AIs are associated with a higher fracture rate compared to tamoxifen. Clinical trials with over 100 months of follow-up, suggest that the fracture risk is not significant after treatment is completed However, current evidence is limited: Highly restricted patient population, which may not be representative of the “real world” There is an under-representation of older women with increased baseline fracture risk Study design Retrospective population-based cohort design, using administrative databases in Ontario Study population Women aged 66 years and older Women in Ontario diagnosed with invasive breast cancer Diagnosed between April 1, 1996 and March 31, 2006 Underwent breast cancer surgery within 1 year of diagnosis Were alive at 365 days from diagnosis Commenced taking hormone therapy within 1 year of diagnosis Exposure There were two exposure categories: AI or Tamoxifen started within 1 year of diagnosis Exposure was based on drug claims from the Ontario Drug Benefit database: First prescription within 1 year of diagnosis Second prescription within 150% of days of the first prescription Outcomes Primary: Fracture Emergency Room (ER) visit or hospitalization for fracture Spine, hip, lower extremity, upper extremity, wrist/forearm Excludes: in context of trauma or pathologic fracture Follow-up Begins 365 days after cancer diagnosis There is at least a 3-year follow-up allowed for each woman in the cohort Patients will be followed from diagnosis until the first occurrence of Fracture Death Cancer recurrence or new malignancy End of follow-up window (March 31, 2009). Ongoing Analysis Descriptive statistics among users of tamoxifen and AI Patient characteristics, health care usage patterns, pre-existing risk factors for fall and fracture Relationship between hormonal therapy and fracture Cox proportional hazards regression analysis Stratified analyses by previous fracture or osteoporosis Special Considerations Competing risks analysis (death, cancer recurrence) To examine the fracture risk in users of hormone therapy To examine the fracture risk with HT, stratifying by pre-treatment osteoporosis or previous fracture Look-back Window (up to 5 years) Observation Window (April 1997- March 2009) Breast cancer diagnosis Accrual Window (April 1996-March 2006) Maximum Follow-up Date (March 2009) Time Study-specific Dates 1 year We would like to thank Lingsong Yun, Sunila Kalkar, Wei Wu and Peter Anderson for their technical assistance. This study was conducted with the support of funding provided by the Ontario Institute for Cancer Research and Cancer Care Ontario (through funding provided by the Ministries of Health and Research & Innovation of the Government of Ontario). This study is also supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred. Background Objectives Implications These data indicate that fractures are common in this population It is important to further examine which women are at higher risk for fracture, while taking HT as adjuvant therapy for breast cancer. This will help: Facilitate informed therapy selection Guide targeted prevention, monitoring, early intervention 9348 women were identified in the cohort Overall rates of fracture in the entire cohort were 5.8% for hip fractures and 2.8% for spine fractures 7992 (85%) prescribed Tamoxifen and 1356 (15%) were prescribed AI The mean (SD) age was 74.8 (6.3) years Treatment duration yr (SD): 3.03 (1.55) Median Follow up yr (IQR).: 4.13 (2.29-6.69) Hip Spine Fracture Rate (%)