About 90% of cancers have been linked to nongenetic factors—environmental exposures and lifestyle choices such as smoking—but the evidence that psychosocial factors such as stress might increase cancer risk is tentative. In theory, stress could play a role in increasing cancer risk through its association with the physiological stress response, which is characterized by increased secretion of hypothalamic and pituitary stress hormones. These hormones can trigger and maintain chronic inflammation, which has been shown to play various roles in cancer promotion and progression.
To study this possibility, researchers from the IPD-Work (Individual-participant-data meta-analysis of working populations) Consortium, led by the Finnish Institute of Occupational Health and University College London, performed a meta-analysis of 12 European cohort studies. This analysis included 116 056 men and women aged 17 to 70 years who were free from cancer at study baseline and were followed up for a median of 12 years. Work stress, which was self-reported at baseline, was measured and defined as job strain characterized by a combination of high demands and low control at work, as ascertained by questions answered in the Job Content Questionnaire and Demand-Control Questionnaire.
In the course of the study, 5765 cases of cancer developed among the study participants. The researchers found no association between work stress and an increased risk for cancer in general, nor did they find an association between work stress and colorectal, lung, breast, or prostate cancer. The cancer rates were adjusted for age, sex, socioeconomic position, BMI, smoking, and alcohol use.
The researchers noted that their findings do not preclude other types of psychosocial stress, such as stress from adverse life events, being linked to increased cancer risk, nor did they discuss research suggesting an association between job strain and increased heart disease risk. The authors concluded that although reducing work stress “would undoubtedly improve the psychological and physical wellbeing of the working individuals as well as the working population, it is unlikely to have an important impact on cancer burden at a population level.”