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    Does Adjuvant Breast Cancer Therapy Change Bone Mineral Density in Postmenopausal Women?

    Scientific Abstract:
    Background: Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Osteoporosis negatively effects the quality of life due to disfigurement, lowered self-esteem, reduction or loss of mobility, and decreased independence and further it can be life-threatening when it leads to thromboembolic events or infection as a consequence of bone fracture and treatment. Breast cancer patients may be at increased risk for osteoporosis compared to age-matched controls. Hypogonadism, with the loss of estrogen, and as a consequence of adjuvant therapy, adversely effects maintenance of bone mass and independent of menopausal status. Hence adjuvant therapy for breast cancer may directly exert negative effects on bone. To further explore this relationship the proposed clinical trial will investigate the effects of adjuvant therapy (chemotherapy and/or hormonal therapy) on the bone mineral density of postmenopausal women with early stage breast to define the rate of bone mass loss in such patients undergoing adjuvant breast cancer therapy. Objectives/Hypothesis: The hypothesis of this study is that adjuvant chemotherapy increases the risk of osteoporosis in postmenopausal women. The objective is to describe the effects of chemotherapy and hormonal regimens on bone mineral density and to use this data to inform later prospective study designs. Specific Aims: 1. To serially evaluate bone mineral density in postmenopausal women undergoing adjuvant systemic treatment for early stage breast cancer 2. To descriptively compare the rate of bone mineral density change between the following groups (i) Chemotherapy and adjuvant tamoxifen (ii) Chemotherapy alone (iii) Tamoxifen alone. (iv) Observation alone (v) Chemotherapy and adjuvant aromatase inhibitor (vi) Aromatase inhibitor alone and use the rate of change to identify subgroups of breast cancer patients that may be at increased for osteoporotic fractures. Study Design: This prospective, observational study will gather pilot data on the effects of systemic breast cancer therapy on bone mineral density in postmenopausal women receiving adjuvant care for early stage, operable breast cancer. Postmenopausal women are the focus of this study because: (1) they are the largest subgroup of women with breast cancer, (2) they are expected to have a rate of BMD loss of 0.5-1.0% per year unless disturbed by disease or medications, unlike pre- and peri-menopausal women whose BMD is more dramatically affected by fluctuating changes in hormonal status, (3) they are at greatest risk for acute osteoporotic fractures. The study will be stratified by treatment group: (i) Chemotherapy and adjuvant tamoxifen (ii) Chemotherapy alone (iii) Tamoxifen alone. (iv) Observation alone (v) Chemotherapy and adjuvant aromatase inhibitor (vi) Aromatase inhibitor alone. Patients will have serial bone mineral density assessment annually (baseline, 12 month and 24 month assessment of bone mass). This 2 year observational study will identify the rate of BMD change within the 6 adjuvant treatment subgroups; any bone related disease condition diagnosed during the course of this study will be treated according to standard of care. If any of the 6 treatment groups demonstrates a loss of BMD greater than 1% per year, then this treatment group will become the target for future therapeutic studies designed to maintain BMD. Potential Outcomes: This trial addresses survivorship and potential long term toxicities of breast cancer therapy. Whether a change in BMD is caused by adjuvant therapy remains to be determined and is the focus of this trial. Osteoporosis can negatively affect the quality of life due to disfigurement, lowered self esteem, reduction or loss of mobility, and decreased independence. It can also lead to life-threatening complications. If a correlation between a specific treatment arm and loss of bone mineral density is identified, then prospective clinical trials, specifically targeting that patient subset, would follow to investigate therapeutic interventions to prevent loss of bone mass. The relationship between breast cancer, cancer therapies, and osteoporosis is clinically relevant as selective estrogen receptor modulators, bisphosphonates or novel drugs such as parathyroid hormone or osteoprotegerin-like analogs may demonstrate varying efficacy in breast cancer patients at risk for osteoporotic fractures. To offer optimal individualized therapy in the future we first must define the risk of bone loss associated with specific adjuvant therapies. Then future studies can identify the optimal method(s) of preventing and treating postmenopausal osteoporosis with a diagnosis of breast cancer. Clinical trials designed to optimize interventions by both improving patient selection, as well as studying combination therapies will be designed based on the results of this study.

    Lay Abstract:
    Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Osteoporosis can compromise the quality of life due to chronic pain, spinal deformities and disfigurement, lowered self-esteem, reduction or loss of mobility and independence and the complications of bone fracture, including blood clots and infection, can be life-threatening. Breast cancer patients may be at increased risk for osteoporosis secondary to cancer treatment. This clinical trial will investigate the effects of adjuvant therapy on the bone mineral density of postmenopausal women with early stage breast cancer. The clinical effects of adjuvant breast cancer therapies on bone mineral density in postmenopausal women have not been widely studied. This prospective, observational study will gather data on the effects of systemic breast cancer therapy on bone mineral density in postmenopausal women receiving adjuvant care for early stage, operable breast cancer. Postmenopausal women are the focus of this study because: (1) they are the largest subgroup of women with breast cancer (2) they are expected to have a rate of BMD loss of 0.5-1.0% per year unless disturbed by disease or medications, unlike the pre and peri-menopausal women whose BMD is dramatically affected by changes in hormonal status (3) this group of patients is at greatest risk for acute osteoporotic fractures. The study will be stratified by treatment group: (i) Chemotherapy and adjuvant tamoxifen (ii) Chemotherapy alone (iii) Tamoxifen alone. (iv) Observation alone (v) Chemotherapy and adjuvant aromatase inhibitor (vi) Aromatase inhibitor alone. Patients will have serial bone mineral density assessments (baseline, 12 month and 24 month assessment of bone mass). This 2 year observational study will identify the rate of bone mineral density within the 6 adjuvant treatment subgroups defined above. Any disease condition diagnosed during the course of this study will be treated according to standard of care. If any of the 6 treatment groups demonstrates a loss of BMD greater then 1% per year, this treatment group will become the target of future therapeutic studies designed to maintain BMD. This trial addresses survivorship and potential long term toxicities of breast cancer therapy. If a correlation between a specific treatment arm and loss of bone mineral density is identified, then clinical trials would follow to investigate therapeutic interventions to prevent loss of bone mass for those at increased risk. As selective estrogen receptor modulators, bisphosphonates or novel drugs (such as parathyroid hormone or osteoprotegerin-like analogs) may demonstrate varying efficacy in certain subsets of breast cancer patients at risk for osteoporotic fractures, the relationship between breast cancer, cancer therapies and osteoporosis is particularly relevant. To address this challenge, we first must define the risk of bone loss associated with adjuvant therapy, and then future clinical trials can be designed to decrease this risk.