ABSTRACT

The role of psychosocial exposures in the development of malignant disease is an old notion, but only in the past decades has the relationship between psychosocial factors and incident cancers been examined in large-scale prospective epidemiological studies, systematic reviews and meta-analyses. This chapter describes this evidence base, focusing on the most commonly studied exposures: stress, personality traits and mental health. Scientific literature on the relationship between stress exposures and different cancer types is vast and heterogeneous in terms of study designs, exposures and outcomes. Currently available evidence suggests that work-related stress, post-traumatic stress disorder, anxiety or personality traits are unlikely to be risk factors for malignant diseases. Some studies point to possible associations of stressful life events and depression with an increased incidence of and mortality from certain cancers. However, difficulties in adequately quantifying psychosocial exposures and potential biases affecting many studies pose challenges to the interpretation of this evidence. Psychosocial exposures can influence the functioning of the endocrine and immune systems and lead to people making less-healthy lifestyle choices, which in turn can impact on the risk of developing cancer. Overall, however, there is no clear evidence of most psychosocial exposures having a direct impact on cancer risk.