London: People who are prone to stress and depression are at an increased risk of cancer.

This finding, involving over 60,000 people will add to the controversy over whether purely psychological factors such as stress, anxiety and depression can trigger cancer, according to a report in ‘New Scientist’.

Part of the problem with this kind of study is that it is hard to exclude with certainty the influence of behavioural factors, such as lack of self-care, poor diet and smoking.

A team of psychiatrists led by Arnstein Mykletun at the University of Bergen in Norway followed up 62,591 people. They found that those who scored highly in an anxiety test in 1995 were about 25 per cent more likely to have pre-malignancies, the report said.

Previous studies have also found an association between psychological stress and two specific types of tumours, lymphomas and malignant melanomas. These results are intriguing, as lymphomas and melanomas are linked with immune system dysfunction.

One theory is that psychological states like stress, anxiety or depression lower immune activity, compromising the body's constant surveillance for pre-malignant or cancerous cells and thus allowing cancers to grow, the report noted.

Support for this theory comes from another study presented at the San Francisco meeting. Sandra Nunez’s team at the State University of Landline in Brazil compared 40 depressed adults and found that in the depressed patients, there were dramatic reductions in immune functions, including white blood cell activity and antibody responses, it added.

ANI