It is not the kind of news that will help matters. A study involving over 60,000 people suggests that people prone to anxiety are more likely to get cancer.
The findings will add to the controversy over whether purely psychological factors such as stress, anxiety and depression can trigger cancer. 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 who took part in a massive medical survey of people living in one county in Norway during 1995 to 1997. The Norway National Cancer Registry was used to identify participants in the survey who had developed cancers or premalignancies – abnormal cells that can turn cancerous.Those who scored highly in an anxiety test in 1995 were about 25 per cent more likely to have premalignancies, the team told a meeting of the American Psychiatric Association in San Francisco last week.Inconsistent results Previous studies of the link between mind and cancer have produced inconsistent results, Susanne Oksbjeg Dalton’s team at the Institute of Cancer Epidemiology in Copenhagen, Denmark, concluded in the most recent review. But two studies did find 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 premalignant or cancerous cells, and thus allowing cancers to grow.Support for this theory comes from another study presented at the San Francisco meeting. Sandra Nunes’s team at the State University of Londrina in Brazil compared 40 depressed adults who were not on medication with 34 healthy controls. In the depressed patients, there were dramatic reductions in immune functions, including white blood cell activity and antibody responses. However, Mykletun’s team did not find a statistically significant link between depression and premalignancies in the Norwegian study, as they did with anxiety. Dalton also points out that it is vital that factors like smoking are adequately controlled for in research of this type. People suffering psychological stress are more likely to smoke, greatly increasing their risk of cancer. Mykletun’s team did try to take this into account, but screening for smokers and determining how much they smoke is difficult in large studies like the Norwegian one.The debate looks set to run and run. Until it is resolved, anxious people will have one more thing to worry about.(Source: New Scientist: Raj Persaud: 28th May 2003)