The combinatory effects of natural products and chemotherapy drugs and their mechanisms in breast cancer treatment

Breast cancer is the leading cause of cancer-related death among females. The global morbidity and mortality associated with breast cancer have recently been increasing. Surgery, radiation therapy, chemotherapy, endocrine therapy and biotargeted therapy, alone or in combination, are commonly used for breast cancer treatment. However, diverse side effects can be caused by the current treatments. Natural products derived from plants have almost no toxicity and side effects, with many functions and therapeutic activities. Many preclinical studies have reported the potential of natural products to enhance the effects of chemotherapy drugs in breast cancer treatment. The combined effects of these treatments in breast cancer are summarized in this review, as well as the in vivo and in vitro mechanisms. Natural products enhanced anti-cancer effects and apoptosis via the EGFR, PI3K-Akt, Wnt and other pathways. The toxicity, side effects, and drug resistance were reduced with the combination therapies. The combination of chemotherapy drugs and natural products could be a promising and effective strategy to treat breast cancer.