Work-related stress is not linked to the development of colorectal, lung, breast or prostate cancers, according to a new study.
Around 90 percent of cancers are linked to environmental exposure, according to the research, which notes that while some exposures are well-recognized, such as UV radiation and smoking, others, including psychological factors such as stress, are not.
However, stress can cause chronic inflammation, which has been shown to have a role in the development of cancer, the researchers said, adding that stressed individuals are more likely to smoke, drink alcohol and be obese — all of which are cancer risk factors.
Only a few studies have examined the association between work-related stress and cancer risk and these had unclear conclusions, according to researchers from the IPD-Work Consortium, led by the Finnish Institute of Occupational Health and University College London. That led them to carry out a meta-analysis of 12 studies involving 116,000 participants aged 17 to 70, from Finland, France, the Netherlands, Sweden, Denmark, and the UK.
According to the researchers, psychological stress at work was assessed using a validated measure, job strain. Job strain was categorized into 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 was obtained from national cancer or death registries and hospitalization registries.
Rates were adjusted for age, sex, socioeconomic position, smoking, alcohol intake and BMI. Those with a BMI under 15 or over 50 were excluded from the study, according to the researchers.
Results showed that 5,765 of 116,056 participants — or 5 percent — developed some form of cancer in the average 12-year follow-up.
Researchers conclude that the meta-analysis provided “no evidence for an association between job strain and overall cancer risk” suggesting that work-related psychological stress is unlikely to be an important factor for cancer.
They also suggest that many of the previously reported associations may have been chance findings or influenced by possible unmeasured common causes of stress and cancer, for example, shift work.
Source: British Medical Journal