Chinese expert consensus on endocrine therapy for breast cancer (2026 edition)

Background: Endocrine therapy (ET) is the primary treatment for hormone receptor (HR)-positive breast cancer. Based on the 2023 expert consensus, the Chinese Consensus Group on Breast Cancer Endocrine Therapy updated this consensus by integrating clinical research data and practical experiences. Methods: (I) Establishment of expert group: the expert group consists of experts from departments such as medical oncology, breast surgery, and pathology. (II) Literature search: mainly conducted in English databases (such as PubMed, Embase, and Cochrane Library) with a search cutoff date of Sep 30th 2025. (III) Assessment of evidence quality and recommendation strength: evidence quality and recommendation opinions are graded based on the evidence category and recommendation level of the Chinese Society of Clinical Oncology (CSCO) guidelines. Results: The 2026 consensus updated clinical research data on ET for both early and advanced breast cancer, defined the eligible population for neoadjuvant ET, and clarified the application of adjuvant cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy in moderate and high-risk patients. For advanced breast cancer, the consensus optimized the treatment strategy of first-line ET plus CDK4/6i, and recommended preferred post-CDK4/6i regimens for patients with distinct clinic-pathological characteristics. It also provides clear recommendations on the indication, optimal timing, and methodology of genetic testing. Conclusions: This consensus may provide clinical guidance for the standardized application of ET, thereby facilitating precise and individualized treatment for HR-positive breast cancer.