Biotechnology Healthcare - June 2008 - (Page 26) CASE STUDY Comparing aromatase inhibitors with tamoxifen for early-stage breast cancer Even though breast cancer mortality is decreasing, its incidence is increasing (Cianfrocca 2005), raising the concern that breast cancer is evolving into a chronic condition for which expensive treatments may continue indefinitely. For payers, this has heightened the importance of ensuring that patients identified with early-stage breast cancer receive the most efficacious care. Treatment for early-stage breast cancer has been studied extensively, and the current standard of care is “…to administer adjuvant systemic therapy to patients with node-positive and highrisk, node-negative breast cancer” (Cianfrocca 2005). But which systemic therapy should be used? For the purposes of this case study, we focus on aromatase inhibitors (AIs) versus tamoxifen. TABLE 2 Comparison of the few head-to-head clinical trials evaluating AIs versus tamoxifen shows a favorable absolute difference for AIs in rates of disease-free survival and overall survival, with a slightly reduced rate of endometrial cancer and a higher rate of osteoporosis (Table 2). Tamoxifen is considered the standard-of-care adjuvant therapy for patients with high-risk breast cancer; therefore, it provides a good comparator for evaluating efficacy and safety of agents within this class. For payers, the key question is whether the difference in cost of the AIs over tamoxifen is justified by the data. Patients and providers need to focus on whether the increased efficacy of AIs compared with tamoxifen is offset by the tradeoffs in adverse events. Comparing aromatase inhibitors with tamoxifen Absolute difference Adverse events Hot Endometrial flashes cancer 36% 0.2%* Thromboembolic events 4.5%* Bone fracture/ osteoporosis 11%† Drug Anastrozole vs. tamoxifen DFS OS Trial ATAC, AIs started immediately postsurgery; 3,215 patients in the anastrozole arm, 3,116 in the tamoxifen arm BIG 01-198, AIs started immediately postsurgery; 4,003 patients in the letrozole arm, 4,007 in the tamoxifen arm IES, AIs started after 2 to 3 yrs of tamoxifen; 2,362 patients in the exemestane arm, 2,372 in the tamoxifen arm 2.4% 0.3% Letrozole vs. tamoxifen 1.9% 0.7% 34% 0.2% 2.0%* 5.8%* Exemestane vs. tamoxifen 3.5% 0.6% 42% NR 1.9%* 7.4%* AI=aromatase inhibitors; ATAC=arimidex, tamoxifen alone or in combination; BIG=Breast International Group; DFS=disease-free survival; IES=International Exemestane Study; NR=not reported; OS=overall survival. *Difference statistically significant in favor of AI. †Difference statistically significant in favor of tamoxifen. Table should not be used to compare AIs, as trial designs differed. These agents’ comparisons to tamoxifen are valid only in the context of each individual trial. Sources: Nordman 2005, Masakazu 2006 26 BIOTECHNOLOGY HEALTHCARE · MAY/JUNE 2008
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