LONDON - People who are anxious or depressed are far more likely to die from cancer, according to a new study.
Researchers in Britain reviewed the findings of 16 studies involving 163,000 people to establish how feeling worried and withdrawn impacts survival.
Overall, the people who were most distressed by their diagnosis were 32 per cent more likely to die from their cancer.
The study was carried out by researchers from University College London and the University of Edinburgh and was published in the British Medical Journal.
For individual cancers, the relationship was even more stark. People suffering from leukaemia were almost four times more likely to die if they were anxious or depressed, while those with prostate, pancreatic or oesophageal cancer were more than twice as likely to not survive.
Dr David Batty, the report's lead author from UCL, said: "The results show that - compared with people in the least distressed group - death rates in the most distressed group were consistently higher for cancer of the bowel, prostate, pancreas, and oesophagus and for leukaemia.
"Our findings contribute to the evidence that poor mental health might have some predictive capacity for certain physical diseases."
Previous research has shown that mental distress is related to increased rates of heart disease, but it was unknown if it could affect survival rates in cancer, said a Daily Telegraph report on the findings.
To find out, participants were monitored for an average of nine and a half years and questioned about their mental state. During the study, more than 4,000 people died from cancer.
Those who died in the first five years were excluded in case the undiagnosed cancer was driving their depression and anxiety. The researchers also adjusted for age, sex, education, socio-economic status, Body Mass Index, smoking and alcohol intake, and the effect still remained.
Last week, scientists at Harvard found that people who have heightened activity in a part of the brain linked to stress - the amygdala - are more likely to develop cardiovascular disease, said the Telegraph.
The amygdala is responsible for telling the bone marrow to temporarily produce more white blood cells that fight infection and repair damage.
It essentially prepares the body for a harmful experience, such as being punched, and would have been vital to survival in our evolutionary past.
However, in the modern world, chronic stress can lead to an over-production of white blood cells, which can form plaques in the arteries and lead to heart disease, scientists believe.
In the new paper, said the Telegraph, scientists speculate that chronic stress also diminished immune cell function and allowed tumours to get a foothold and grow.
Yale University has also previously proven that stress can cause cancer in fruit flies.
