Abstract P1-09-03: A Pharmaco-Economic Analysis of Tamoxifen (T) vs. Aromatase Inhibitors (AI) in Adjuvant Treatment of Postmenopausal (PoM) Women (W) with Hormone Receptor Positive (HRP) Breast Cancer (BC)

Abstract

Abstract Background: Endocrine Therapy (ET) is an important component of adjuvant therapy in PoM W with HRP BC.AI are the preferred modality of ET despite higher cost. We performed an analysis to determine the cost of the difference in BC specific survival benefit when using AI compared to T in the adjuvant treatment of HRP BC in PoM W. Methods: Prices of medications were obtained through First Data Bank Blue Book. Annual incidence of BC globally was taken as reported in GLOBOCAN 2008. Incidence of non-metastatic, HRP BC in PoM W was calculated using data on incidence of metastatic BC (6%), HRP BC (80%) and W with PoM status (75%) from Cancer Statistics 2009 and Anderson WF et al, 2002 respectively. Meta-analysis of ATAC and BIG-98 trials comparing 5 years (yrs) of T and AI (T and anastrozole/letrozole), in the adjuvant setting presented by Dowsett et al, JCO, Vol 28, No 3 (January 20), 2010: 509-518 was used for calculating BC specific survival benefit of AI over T. Results: Annually, 780,307 W globally would be eligible for 5 yrs of adjuvant ET. The cost of 5 yrs treatment for these W with T vs. AI is $5.4 billion (B) United States dollars (USD) vs. $22.5 B USD, respectively. The absolute BC specific survival benefit of treating W with AI over T for 5 yrs was 1.1%. Therefore, treating 780,307 women with AI rather than T for 5 yrs would benefit about 8583 W from BC specific mortality. The cost for saving one woman from BC related mortality, if treated with AI rather than T would be $1,992310.38 USD [(22.5 B USD — 5.4 B USD/8583]. AI use was associated with fewer endometrial cancers and thromboembolic events than T but with more arthralgias and fractures. Conclusion: AIs have shown benefit over T, but applying those results en-mass to all patients with HRP BC might be a substantial economic burden on society with relatively small benefits. Target markers for subset of patients who might preferentially benefit from AIs more than T need to be identified to best optimize the benefit from these drugs. Each class of drugs have different side effect profiles which should help individualize treatment. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-03.