Glucocorticoids, stress and cancer: New insights in immune system and tumour cell regulations

Glucocorticoids and catecholamines are considered the main stress hormones, which are produced after the activation of the hypothalamic-pituitary adrenal axis (HPA) and the autonomic nervous system (ANS) induced by an aversive stimulus. Interestingly, exposure to stressful situations has been associated with alterations in the incidence, progression and outcome of neoplastic processes. In addition, corticoids are often coadministered in cancer patients as adjuvant treatment to chemo and radiotherapy. Cortisol has been proposed as one of the hormones responsible of these alterations, in part given that stress and glucocorticoids alter different components of the immune system such as lymphocyte proliferation, cytotoxic and fagocytic activity, antibody and cytokine production, and redistribution of immune cells among the different lymphoid organs. In addition, glucocorticoids have direct effects on cancer cells, for example, they modulate the expression of genes related to chemotherapy resistance, survival and apoptosis evasion in certain tumours. Moreover, some oncogenic virus such as human papilloma, hepatitis and Epstein-Barr viruses are susceptible to be regulated by glucocorticoids. Here we review all these items and analyse the recent advances in this field obtained using animal models and clinical studies. Also, we discuss the novel discovery of the involvement of hypothalamic-pituitary thyroid (HPT) axis in these processes, and the regulation exerted by the HPA on thyroid hormones.