Cost-Effectiveness Analysis of Hormone Therapy for Breast Cancer in Japan

Breast cancer is one of the deadliest diseases in the world. It accounts for 22.2% of all cancers and is the most common site of cancer in women in Japan. Although hormone therapy with aromatase inhibitors or tamoxifen has been widely used, it is unclear which agent is more cost-effective. This study examined the cost-effectiveness of anastrozole as an aromatase inhibitor from a healthcare payer's perspective compared to tamoxifen in Japan.

A Markov model, for comparing anastrozole with tamoxifen as a reference agent, was developed using data from a randomized clinical trial conducted in Japan. The costs were derived from the Japanese health care fee index for 2022. Based on the results of a questionnaire on the general health-related quality of life associated with cancer (FACT-G), utilities were converted to EuroQol-5 Dimension-5 Level. The time horizon was set to 10 years. In addition, deterministic and probabilistic sensitivity analyses were conducted.

Anastrozole was dominated by tamoxifen. Deterministic one-way sensitivty analysis showed the expected value (EV) of incremental net monetary benefit for anastrozole was the highest sensitive to the pharmaceutical "drug price of anastrozole in fiscal year (FY) 2022," where the generic drug price was applied. The EV remained negative across the other parameters. Probabilistic sensitivity analysis revealed that anastrozole dominance over tamoxifen was 47.2%.

Anastrozole was less cost-effective than tamoxifen in Japan. Our findings support clinical practice and suggest that payers and policymakers should promote cost-effective therapies.