Optimizing endocrine adjuvant therapy in HR+/HER2- breast cancer: supplemental strategies and innovations

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.