Lidia Schapira1,2, Allison W Kurian3,4,5, Tanya Gupta1, Natasha Purington6, Mina Liu6,7, Summer Han6,2, George Sledge1. 1. Department of Medicine, Division of Medical Oncology, Stanford University, Stanford, CA, USA. 2. Stanford Cancer Institute, Stanford, CA, USA. 3. Department of Medicine, Division of Medical Oncology, Stanford University, Stanford, CA, USA. akurian@stanford.edu. 4. Stanford Cancer Institute, Stanford, CA, USA. akurian@stanford.edu. 5. Department of Epidemiology and Population Health, Alway Building, M121M, Stanford, CA, 94305, USA. akurian@stanford.edu. 6. Quantitative Sciences Unit, Division of Biomedical Informatics Research, Department of Medicine, Stanford University, Stanford, CA, USA. 7. Research Informatics Center, Stanford University, Stanford, CA, USA.
Abstract
PURPOSE: As survival with early-stage, hormone receptor (HR)-positive breast has improved, it is essential to understand the long-term risks of incident comorbidities with different adjuvant endocrine therapy (ET) options. METHODS: Women treated with tamoxifen and/or an aromatase inhibitor (AI) for stages 1-3, HR-positive/HER2-negative breast cancer from 2000 to 2016 in either of two healthcare systems in the San Francisco Bay Area were included. We considered the following comorbidities: cerebrovascular accidents, congestive heart failure, dementia, depression/anxiety, diabetes mellitus, hyperlipidemia, myocardial infarction, non-alcoholic steatohepatitis, osteoporosis/fracture, peripheral vascular disease, and venous thromboembolism. Cause-specific Cox proportional hazards models were fit to time-to-new-diagnosis for each comorbidity, accounting for death as a competing risk. Hazard ratios (HR) and 95% confidence intervals (CI) for tamoxifen versus AI were reported. RESULTS: Among 2,902 analyzed patients, the median age at diagnosis was 58.3 years; 67.6% were non-Hispanic white, 22.3% Asian, 7.5% Hispanic, and 1.7% non-Hispanic Black. Half (54.7%) used AIs only, 27.6% used tamoxifen only and 17.7% used both tamoxifen and AIs sequentially. Tamoxifen was associated with a lower risk of osteoporosis than AI (multivariable HR 0.45, 95% CI 0.32-0.62). No other incident comorbidity risk varied between users of tamoxifen versus AIs. CONCLUSION: In a diverse, multi-institutional, contemporary breast cancer cohort, the only incident comorbidity that differed between ET options was osteoporosis, a known side effect of AIs. These results may inform clinical decision-making about ET, and reassure patients who have bothersome symptoms on AIs that they are unlikely to develop worse comorbidities if they switch to tamoxifen.
PURPOSE: As survival with early-stage, hormone receptor (HR)-positive breast has improved, it is essential to understand the long-term risks of incident comorbidities with different adjuvant endocrine therapy (ET) options. METHODS: Women treated with tamoxifen and/or an aromatase inhibitor (AI) for stages 1-3, HR-positive/HER2-negative breast cancer from 2000 to 2016 in either of two healthcare systems in the San Francisco Bay Area were included. We considered the following comorbidities: cerebrovascular accidents, congestive heart failure, dementia, depression/anxiety, diabetes mellitus, hyperlipidemia, myocardial infarction, non-alcoholic steatohepatitis, osteoporosis/fracture, peripheral vascular disease, and venous thromboembolism. Cause-specific Cox proportional hazards models were fit to time-to-new-diagnosis for each comorbidity, accounting for death as a competing risk. Hazard ratios (HR) and 95% confidence intervals (CI) for tamoxifen versus AI were reported. RESULTS: Among 2,902 analyzed patients, the median age at diagnosis was 58.3 years; 67.6% were non-Hispanic white, 22.3% Asian, 7.5% Hispanic, and 1.7% non-Hispanic Black. Half (54.7%) used AIs only, 27.6% used tamoxifen only and 17.7% used both tamoxifen and AIs sequentially. Tamoxifen was associated with a lower risk of osteoporosis than AI (multivariable HR 0.45, 95% CI 0.32-0.62). No other incident comorbidity risk varied between users of tamoxifen versus AIs. CONCLUSION: In a diverse, multi-institutional, contemporary breast cancer cohort, the only incident comorbidity that differed between ET options was osteoporosis, a known side effect of AIs. These results may inform clinical decision-making about ET, and reassure patients who have bothersome symptoms on AIs that they are unlikely to develop worse comorbidities if they switch to tamoxifen.