Methods

1. Study-specific Dates Maximum Follow-up Date (March 2009) Accrual Window (April 1996-March 2006) Time Look-back Window (up to 5 years) 1 year Observation Window (April 1997- March 2009) Breast cancer diagnosis Background • 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 Objectives • 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 Description of fracture with endocrine therapy use in older breast cancer survivors in a population-based settingTaryn Becker123, Geoff Anderson123, Thiwanka Wijeratne123, Lorraine Lipscombe123, Andrea Gruneir123 , Ophira Ginsburg123, Amy Finch13, Paula Rochon123 1. Women’s College Research Institute 2. Institute for Clinical Evaluative Sciences 3. University of Toronto Methods Preliminary Results • 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) • . • 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) Fracture Rate (%) Spine Hip Work in Progress • 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) 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 Acknowledgements 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.