The molecular mechanism of chronic stress affecting the occurrence and development of breast cancer and potential drug therapy.

According to the 2020 data released by the International Agency for Research on Cancer, breast cancer has surpassed lung cancer as the world's most newly diagnosed first-time cancer. Compared with patients with other types of cancer, those with breast cancer experience greater mental stress and more severe psychological impacts because of the life-threatening diagnosis, physical changes, treatment side effects, and family and social life dysfunctions. These usually manifest as anxiety, depression, nervousness, and insomnia, all of which elicit stress responses. Particularly under chronic stress, the continuous release of neurotransmitters from the neuroendocrine system can have a highly profound impact on the occurrence and prognosis of breast cancer. However, because of the complex mechanisms underlying chronic stress and the variability in individual tolerance, evidence of the role of chronic stress in the occurrence and evolution of breast cancer remains unclear. This article reviewed previous research on the correlation between chronic stress and the occurrence and development of breast cancer, particularly the molecular mechanism through which chronic stress promotes breast cancer via neurotransmitters secreted by the nervous system. We also review the progress in the development of potential drugs or blockers for the treatment of breast cancer by targeting the neuroendocrine system.