Advances and controversies in the adjuvant treatment of early breast cancer

Breast cancer is one of the common malignant tumors among women worldwide, and with advances in screening and diagnostic technology, more and more breast cancer patients are being diagnosed at an early stage. Adjuvant treatment options for different types of early-stage breast cancer vary. In recent years, the development of treatment strategies has focused on maximizing the efficacy of treatment while avoiding over-treatment based on the patient’s individual risk profile. For hormone receptor (HR)-positive breast cancer, the introduction of cell cyclin-dependent kinase (CDK)4/6 inhibitors has significantly improved the prognosis of intermediate- and high-risk patients. Meanwhile, chemotherapy de-escalation strategies based on genetic testing are also advancing. However, controversies remain regarding which patients can benefit from CDK4/6 inhibitor-enhanced therapy and whether premenopausal patients with intermediate-risk classification from multi-gene assays can gain benefits from chemotherapy. In human epidermal growth factor receptor 2 (HR)-positive breast cancer, anti-HER2 targeted therapies and novel antibody-drug conjugate provide more effective treatment options. However, how to screen the optimal population for dual-targeted therapy is still under exploration, and currently there is no consensus on how to select subsequent intensified regimens for patients who fail to achieve pathological complete response after neoadjuvant therapy. For triple-negative breast cancer, while traditional adjuvant therapy has been continuously optimized, the application of immunotherapy in the neoadjuvant and adjuvant phases has also made significant progress. Nevertheless, the definition of the optimal population to benefit from immunotherapy and the optimization strategy of immunotherapy are still key areas of ongoing research. This review summarized the advancements and controversies in adjuvant therapy for early breast cancer, aiming to provide references for current clinical practice and insights for future research directions.