Background <p>The MONARCH 3 trial has demonstrated that Anastrozole combined with Abemaciclib is safe and effective for the treatment of postmenopausal hormone receptor-positive advanced breast cancer. However, its cost-effectiveness for long-term use has not been investigated yet. This study aims to evaluate the cost-effectiveness of Anastrozole combined with Abemaciclib versus Anastrozole used alone for patients in China.</p> Methods <p>Based on MONARCH 3 trial data, we constructed a Markov model using Treeage Pro 2022 software. The model cycle was set at 1 month over a period of 20- year time horizon, and the annual discount rate was set at 5%. The cost-utility analysis was used to assess the cost-effectiveness of Anastrozole combined with Abemaciclib for the treatment of postmenopausal hormone receptor-positive advanced breast cancer. The output indexes of the model were cost and quality-adjusted life year (QALY), and the model evaluation index was incremental cost-effectiveness ratio (ICER). The willingness to pay (WTP) threshold was set at 3 times the per-capita gross domestic product (GDP) of China in 2023 (¥268,074/QALY). Meanwhile, one-way sensitivity analysis and probabilistic sensitivity analysis were used to explore the uncertainties of the model and parameters.</p> Results <p>Anastrozole combined with Abemaciclib provided more health benefits than Anastrozole used alone, however, the total cost was higher. The incremental utility and incremental cost were 0.01 QALYs and ¥1075.51, respectively. And the ICER of the two regimens was ¥93,940.83/QALY, which was less than 3 times the per-capita GDP of China in 2023 (¥268,074). The results of the sensitivity analysis attested that the study results were robust.</p> Conclusions <p>Anastrozole combined with Abemaciclib is more cost-effective than Anastrozole used alone for the treatment of postmenopausal hormone receptor-positive advanced breast cancer.</p>