Breast cancer has become the most prevalent malignant tumor worldwide and remains one of the leading causes of cancer-related mortality among women globally. The prognosis for patients with metastatic breast cancer remains poor, necessitating the exploration of novel therapeutic strategies to improve survival rates. In the era of precision medicine, antibody-drug conjugates (ADCs) have gained significant attention as a targeted therapeutic strategy in breast cancer treatment. ADCs, a relatively new treatment for breast cancer, deliver cytotoxic drugs (payloads), directly into the tumor space, turning chemotherapy into a targeted agent, which enables patients to experience significant improvements with manageable drug toxicity. For the treatment of breast cancer, there are three ADCs approved for breast cancer treatment: Trastuzumab emtansine (T-DM1), Trastuzumab Deruxtecan (T-Dxd) targeting HER-2, and Sacituzumab Govitecan (SG) targeting Trop-2. Recent clinical studies have demonstrated that the benefits of ADC therapies extend beyond HER2-positive breast cancer toinclude hormone receptor (HR)-positive breast cancer, triple-negative breast cancer (TNBC), and HER2-low expressing breast cancer. Notably, the DESTINY-Breast series of studies, particularly focusing on T-Dxd, encompass neoadjuvant, adjuvant, and multiple lines of therapy for advanced breast cancer. This marks the advent of a comprehensive ADC era in breast cancer treatment. This review summarizes the efficacy and adverse effects of ADC therapies that have completed or are currently undergoing phase I-III clinical trials. Additionally, it analyzes potential combination strategies to overcome ADC resistance, aiming to provide clinicians with a comprehensive clinical guide to the use of ADCs in breast cancer treatment.

Endocrine therapy (ET) is a cornerstone in adjuvant therapy for hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2−) breast cancer. However, recent research challenges the conventional 5-year adjuvant therapy duration. Patients with T1N0M0 HR+/HER2− breast cancer face a 13% risk of distant recurrence after 5 years of endocrine treatment. This risk increases to 34% over two decades for patients with 4–9 lymph node metastases. Thus, it is important to consider supplementary treatments for T1N0M0 HR+/HER2− breast cancer patients, particularly those with additional high-risk features such as young age, high tumor grade, or adverse genomic profile. We summarize intensive treatment methods for T1N0M0 HR+/HER2− breast cancer patients, which extend beyond the standard 5-year tamoxifen (TAM)-based adjuvant ET. These methods include intensive ET, poly(ADP-ribose) polymerase (PARP) inhibitors, other targeted therapies, antibody-drug conjugates, oral chemotherapy, immunotherapy, and enhanced prevention of bone metastasis. This review provides a foundation for developing personalized adjuvant treatment strategies for patients with T1N0M0 HR+/HER2− breast cancer.