Chapter 9 - Cancer, Autoimmunity, and Psychosocial Stress

Abstract

This chapter examines diseases that arise when self-tissues become malignant or when immune activity is directed at healthy tissue. Genetic factors play a role in creating susceptibility to cancer and autoimmune disorders. In the case of cancer or neoplastic disease, the threat arises from within. The individual's own cells undergo transformation so they multiply uncontrollably and compete with healthy tissue for both space and resources. It is now understood that a cancer is an expanding clone. It begins when a single cell becomes transformed, through the accumulation of specific genetic mutations, so that it reproduces frequently and remains insensitive to signals for growth inhibition. The genes that appear mutated in cancer cells are typically those that are involved in some aspect of cell growth. The p53 gene is believed to be the most commonly mutated gene in human cancer. The p53 protein functions in the activation of cell death in response to deoxyribonucleic acid (DNA) damage. Females are at higher risk of autoimmune disorders. The phases of their reproductive function appear to modulate autoimmunity, probably because of hormonal effects on immune function.