Fig. 2.

Proposed mechanisms through which social isolation influences breast cancer outcomes in women. Socially isolated individuals tend to exhibit increased activation of the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS). Among patients with breast cancer (BC), increased cortisol is associated with reduced natural killer cell (NKC) count and cytotoxicity, and increased risk of early mortality. There is also the supposition that increased concentrations of endogenous catecholamines (adrenaline and noradrenaline) promote tumor development, metastasis, and tumor progression because the use of β_1/β₂ receptor antagonists for other health conditions is associated with less aggressive tumors and reduced early mortality among patients with BC