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Comp. Math. Methods in Medicine. 01/2012; 2012.
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ABSTRACT: We present a mathematical model that lends support to the hypothesis that estrogen levels mediate the complex relationship between body mass index (BMI), menopausal status, estrogen-only hormone replacement therapy (HRT), and breast cancer risk. The model predicts a decrease in the relative risk of breast cancer of 3% per unit increase in BMI (kg/m(2)) for premenopausal women and an increase in the relative risk of 4% per unit increase in BMI for postmenopausal women who are not HRT users. When comparing postmenopausal women who use estrogen-only HRT to postmenopausal women who do not use HRT, the model predicts an increased risk of breast cancer associated with use of estrogen that diminishes with increasing BMI, with a relative risk of 1.6 for women with BMI of 18, 1.2 for women with BMI of 25, and 1.0 for women with BMI ≥ 30. Model predictions agree with data from five major epidemiological studies.
Computational and Mathematical Methods in Medicine 01/2012; 2012:792375. · 0.68 Impact Factor
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ABSTRACT: BACKGROUND:Previous cost-effectiveness analyses of tamoxifen therapy account for breast cancer risk reduction during active treatment but not for its persistent protective effect after active treatment.METHODS:A detailed, continuous time, mathematical model of breast cancer and healthcare processes was used to simulate a postmenopausal population aged <55 years in a virtual trial comparing tamoxifen treatment with no treatment for lifetime follow-up. Unlike previous work, the current model of tamoxifen therapy is based on a meta-analysis of 4 randomized, placebo-controlled chemoprevention trials with breast cancer risk reduction continuing for 10 years after treatment termination. Cancer incidence and survival data were derived from Surveillance, Epidemiology and End Results statistics. Noncancer disease incidences, quality-adjusted life year (QALY) utility weights, and costs were derived from the literature.RESULTS:Tamoxifen treatment (vs no treatment) saved 29 QALYs in a population of 1000 postmenopausal women aged <55 years with an additional cost of $333,000 over the population's lifetime (average cost-effectiveness ratio, $11,530 per QALY). Tamoxifen therapy, compared with no treatment, was cost saving when higher risk populations were targeted (5-year risk ≥1.66%). The cost-effectiveness results were sensitive to parameters that characterized menopausal symptoms and adverse side effects of tamoxifen.CONCLUSIONS:The current results indicated that tamoxifen chemoprophylaxis for postmenopausal women aged <55 years is a cost-effective health policy that reduces breast cancer incidence and improves life expectancy. Focusing on a postmenopausal population aged <55 years minimized the threat of adverse events associated with tamoxifen. Cancer 2011. © 2011 American Cancer Society.
Cancer 07/2011; 117(15):3322 - 3331. · 4.77 Impact Factor
