Reducing breast cancer recurrences with CDK4/6 inhibitor treatment of HR-positive, HER2-negative early stage breast cancer from a societal perspective

Background
Hormone receptor (HR)–positive and HER2 receptor–negative breast cancer accounts for two thirds of all breast cancers. In case of distant recurrences, a non-curative strategy is usually implied. Hence, treatment options for early stage breast cancer to prevent metastatic recurrences are desirable. The aim of our study was to estimate the societal effect of reducing breast cancer recurrences by treating Austrian patients with stage II and III HR + /HER2 − breast cancer with CDK 4/6 inhibitors as an adjuvant treatment.

Methods
We developed a 7-state Markov model with a time horizon of 30 years from a societal perspective and compared the follow-up direct and indirect costs between patients who were treated with and without a CDK4/6 inhibitor in the early stage. We distinguished between anatomic stage II/III and nodal status negative/positive subcohorts of patients. We used transition probabilities derived from the clinical trial NATALEE. Based on local registry data, we derived the Austrian female target population and matched it with the target patients of NATALEE.

Results
We identified 1,340 Austrian target patients diagnosed in 2022. In the anatomical stage II and stage III subcohorts, approx. 735 and 236 metastatic cancer years could be saved over 30 years, respectively. We estimated that, thereby, societal costs of about €52 million (discount rate = 3%) associated with cancer recurrences could be saved in the 30-year follow-up. Almost 75% of cost savings resulted from reductions in health care costs and about 25% from productivity gains (incl. unpaid work).

Conclusions
Treating stage II and III HR + HER2 − breast cancer patients with CDK4/6 inhibitors in Austria reduces metastatic breast cancer recurrences, resulting in considerable medical benefits and economic effects.