Although it’s widely believed that high-stressed jobs put people at increased risk of developing cancer, the scientific evidence in support of that assumption is actually quite weak.
True, chronic stress can trigger an inflammatory response in the body, which is itself associated with cancer, but it’s a big jump from that observation to the statement that job-related stress can lead to cancer.
That leap in logic looks even more tenuous today. On Thursday, a group of Finnish researchers published what appears to be the most definitive study to date on the topic. They analyzed all the data from 12 previous studies that were conducted between 1985 and 2008 in six different European countries. These studies involved more than 116,000 participants aged 17 to 70.
The researchers found no good evidence of an association between work-related stress and four of the most common cancers: colon, lung, breast and prostate.
“These findings suggest that work related psychosocial stress is unlikely to be an important risk factor for these cancers,” they write. “Thus, though 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.”
What about other types of stress?
The authors of this meta-analysis make it clear that they looked only at work-related stress. They note that another recent meta-analysis found an association between stress-induced trauma, especially early in life, and the development of breast cancer. They also point to a 2011 French study that found people with brain cancer were more likely to have experienced a traumatic life event than those without the cancer.
But those studies have significant limitations. The French study was a small (122 participants) case-control pilot study that showed only a correlation, not a causation, between adverse life events and cancer. Indeed, the authors of that study also found an equally strong correlation between genetics and brain cancer. And although the breast cancer meta-analysis included a description of the biological reasons why the stress from adverse life events might cause breast cancer, it, too, revealed only a correlation between the two.
Which is why the National Cancer Institute makes these unambiguous statements on its website:
- Psychological stress alone has not been found to cause cancer, but psychological stress that lasts a long time may affect a person’s overall health and ability to cope with cancer.
- People who are better able to cope with stress have a better quality of life while they are being treated for cancer, but they do not necessarily live longer.