The relationship between psychosocial stressors and breast cancer biology

Psychosocial stressors have been firmly linked to cardiovascular, immune, and metabolic disease risk through their effects on human physiology. An association with breast cancer risk has also been hypothesized, with both immune and endocrine-mediated mechanisms postulated to link stress to breast cancer biology. Several epidemiologic studies have been performed in an effort to better define the potential association between psychosocial stressors and breast cancer risk. However, despite large prospective studies, the question of whether or not psychosocial stress influences the risk and/or progression of breast cancer remains controversial. From an epidemiologic standpoint, evidence that chronic stress is linked to increased incidence of breast cancer is mixed, whereas targeted intervention trials suggest that reducing chronic stressors diminishes the risk of recurrence. Experimental approaches using animal studies have also yielded conflicting results depending on the model used. Nevertheless, the experimental studies offer valuable insights into environmental stressors and their potential mechanisms for altering the biology of well-defined breast cancer models. The ultimate goal of studying psychosocial stress and breast cancer biology is to identify the interacting mechanisms linking stress physiology to cancer and thereby to modify breast cancer risk factors.