Stress at work is highly unlikely to be a cause of the four most common types of cancer, according to a large international review of previous research.
Breast, prostate, colorectal and lung cancers are probably not triggered by job-related stress, say the researchers, even though many people assume there is a link. But data from 12 well-conducted trials in six countries between 1985 and 2008, pooled in a meta-analysis which allows scientists to be more certain of their conclusions, shows no increase in cancer among people who are highly stressed by their work.
However, the research does not rule out a link between stress caused by a traumatic life event, such as the unexpected death of a loved one, and cancer. The authors note that in a French study, people with brain cancer were much more likely to report that something disastrous had happened to them than people without the cancer – although there was no clear evidence of a difference in work-related stress levels between the two groups.
The study, published online in the British Medical Journal, pulled together the data from European studies in Finland, France, the Netherlands, Sweden, Denmark and the United Kingdom, involving a total of 116,056 men and women aged 17 to 70. The analysis was carried out by a consortium led by the Finnish Institute of Occupational Health and University College, London.
To measure stress levels at work, researchers looked at job strain, which is generally determined by scientists as the relationship between the degree of control one has over one’s job and the pressure to deliver. So the job strain the participants were experiencing was categorised as: high strain job (high demands and low control), active job (high demands and high control), passive job (low demands and low control) and low strain job (low demands and high control).
Data on cancer events was obtained from national cancer or death registries and hospitalization registries. The findings were adjusted to take account of differences in age, sex, socioeconomic position, BMI, smoking and alcohol intake. Those who were considered underweight or morbidly obese were excluded from the study, since that could have an effect on their stress levels.
Out of the 116,056 participants, 5,765 (5%) developed some form of cancer in the average 12-year follow-up. But the researchers found no evidence that those who were more highly stressed were more likely to get cancer than others.