Abstract 3271: Evaluation of bone health in breast cancer survivors compared to cancer-free women: A prospective study within a young familial risk cohort

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Abstract Background: Bone loss has been consistently reported among long-term older breast cancer (BC) survivors. However, it remains unclear how early and to what degree BC survivors experience bone loss compared to their cancer-free peers and to what extent this can be attributed to age and premature menopause. Methods: We studied 796 women (210 BC survivors, 586 cancer-free) with familial risk of breast and/or ovarian cancer in the Breast and Ovarian Surveillance Service (BOSS) cohort at Johns Hopkins Hospital. Survivors were diagnosed with stage I-III BC <5 years prior to baseline (mean time from diagnosis to enrollment=1.4 years; mean age at diagnosis=47 years). Osteopenia and osteoporosis were ascertained based on self-reported physician diagnosis in baseline and follow-up questionnaires. Prevalent cases of osteopenia or osteoporosis were excluded. Multivariable (MV)-adjusted Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of osteopenia and osteoporosis incidence among BC survivors compared to cancer-free women. MV models were adjusted for age, race, menopause status, body mass index, physical activity, smoking, hormone replacement therapy and early oophorectomy. Results: BC survivors were slightly older (mean age 48 vs. 45 years), more likely to be post-menopausal (51% vs. 29%) and had higher current vitamin D use (21% vs. 8%) compared to cancer-free women. During a mean follow-up time of 6.2 years, 77% of BC survivors and 60% of cancer-free women reported having ≥1 bone density exam and 115 incident osteopenia and/or osteoporosis cases were identified (75% osteopenia only). In MV-adjusted models, BC survivors had 66% higher risk of being diagnosed with osteopenia and/or osteoporosis compared to cancer-free women (HR=1.66, 95% CI=1.11-2.47). BC survivors with no current vitamin D or calcium use had 76% and 93% higher osteopenia and/or osteoporosis risk compared to cancer-free women, respectively (MV HR=1.76, 95% CI=1.14-2.72; MV HR=1.93, 95% CI=1.15-3.24). BC survivors ever treated with chemotherapy or hormone therapy had higher osteopenia and/or osteoporosis risk compared to cancer-free women (MV HR=2.00, 95% CI=1.14-3.50; MV HR=1.79, 95% CI=1.14-2.82, respectively). Analyses restricted to women with no change in menopause status during follow-up were only slightly attenuated (MV HR=1.58, 95% CI=0.96-2.59). Conclusion: Our results demonstrate that bone loss is significantly greater than and occurs early in young BC survivors compared to cancer-free women even after taking into consideration increasing age and premature menopause. Our findings also provide support for a baseline evaluation of bone density at diagnosis with subsequent monitoring in young BC survivors with familial risk. Further analyses are ongoing to evaluate the effect of specific BC treatments on bone health in this cohort. Citation Format: Cody A. Ramin, Betty J. May, Richard B. Roden, Dana Petry, Deborah K. Armstrong, Kala Visvanathan. Evaluation of bone health in breast cancer survivors compared to cancer-free women: A prospective study within a young familial risk cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3271. doi:10.1158/1538-7445.AM2017-3271