Cost-effectiveness of exemestane versus tamoxifen as adjuvant therapy for early-stage breast cancer after 2–3 years treatment with tamoxifen in Sweden

Cost-effectiveness of letrozole, anastrozole and exemestane for early adjuvant breast cancer

Clinical trials have shown aromatase inhibitors to be a more effective hormonal therapy for preventing recurrence in postmenopausal women with hormone receptor-positive early breast cancer. However, the aromatase inhibitors have an alternative adverse event profile and are more expensive than tamoxifen. This review identifies 15 separate cost-effectiveness analyses that have assessed the incremental cost per quality-adjusted life year gained of one or more aromatase inhibitor treatment strategies compared with tamoxifen. We found many similarities between the studies and the overriding conclusion was that the aromatase inhibitor strategies are cost effective relative to 5-year tamoxifen treatment. This conclusion is shared by the National Institute for Clinical Excellence in the UK. Comparisons between the aromatase inhibitors are hampered as none of the clinical trials included a direct comparison, although an ongoing trial is addressing this issue.

Cost-utility of adjuvant hormone therapies with aromatase inhibitors in post-menopausal women with breast cancer: upfront anastrozole, sequential tamoxifen-exemestane and extended tamoxifen-letrozole

This evaluation adapts a previous Canadian analysis of upfront and sequential adjuvant AI strategies in postmenopausal women with breast cancer to a Belgian perspective and includes an extended aromatase inhibitor (AI) strategy. A Markov model calculated monthly costs and outcomes in a hypothetical cohort of postmenopausal women with early-stage breast cancer. Baseline event rates and hazard ratios were derived from the Arimidex, Tamoxifen Alone or in Combination trial, International Exemestane Study and MA.17 trials. The analysis took a Belgian healthcare payer perspective with a 20-year time horizon. Costs and outcomes were discounted by 3%. Costs are in 2005 Euros. The cost-utility of all three strategies was favourable (<30,000 euros per QALY gained). Based on indirect comparisons using tamoxifen (TAM) alone as a common comparator, sequential TAM-AI was less costly and more effective than upfront or extended strategies. All three AI strategies were cost-effective alternatives to TAM alone, but sequential TAM-AI appears to be the economically preferred strategy.

Cost-utility of adjuvant hormone therapies for breast cancer in post-menopausal women: sequential tamoxifen-exemestane and upfront anastrozole

BACKGROUND

Adjuvant Anastrozole (ANA) for 5 years and Tamoxifen followed by Exemestane (TAM-EXE) for 2.5 years each have become acceptable alternatives to 5 years of Tamoxifen (TAM) for post-menopausal women with breast cancer. As these newer options are associated with higher drug costs as well as improved outcomes, an economic evaluation was undertaken to compare the cost-utility of ANA and TAM-EXE relative to TAM alone and to each other in terms of cost per quality-adjusted life year (QALY) gained.

METHODS

A Markov model was developed to calculate monthly costs and outcomes in a hypothetical cohort of post-menopausal women with early-stage breast cancer. Baseline rates of cancer recurrence and adverse effects with TAM, and hazard ratios associated with ANA and EXE, were derived from the ATAC and IES trials. Patients received hormonal therapy for 5 years and benefit was modeled to persist 5 years beyond treatment. The analysis took a direct payer perspective with a 20-year time horizon. Costs and outcomes were discounted by 3%. Costs are in 2005 Canadian dollars.

RESULTS

ANA and TAM-EXE were associated with increased costs and QALYs, though the cost-utility of both relative to TAM alone was strongly favourable (<$50,000/QALY). Based on an indirect comparison of ANA and TAM-EXE, using TAM alone as a common comparator, the cost-utility of ANA relative to TAM-EXE appears unfavourable.

CONCLUSIONS

Both upfront and sequential AI options were cost-effective alternatives to TAM alone, but TAM-EXE appears to be the economically preferred AI option based on its more favourable cost-utility versus ANA.