Breast cancer has the second high prevalence among all types of cancer in the US. The average risk of a woman developing it and dying from the disease stands at 13% and 2.6%, making it the second leading cause of cancer death in women.

Breast cancer subtypes are defined by their histopathological appearance and expression of hormone receptors (HR) and growth factors, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2).

Recent advances in breast cancer treatments provide more approaches to improve the progression-free survival and overall survival rates in patients; developing new agents and strategies can improve drug resistance and efficacy in current treatment. Breast cancer treatments are majorly decided by the cancer stage, subtype, patient's overall health, menopause status, and cancer growth rate.