Could cancer be linked to depression?

26th January 2017 – Anxiety and depression may be linked to a higher risk of dying from some types of cancer, according to a study in The BMJ medical journal.

Researchers in the UK and Australia reviewed some of the available evidence and say that although they can't prove that psychological stress contributes to cancer deaths, the two do appear to have some links.

Mental and physical health

Associations between mental and physical health have been part of mainstream medical thinking for several decades. Also, some previous research has found some evidence that anxiety and depression could increase the likelihood of heart disease. However, no link has been proved between psychological distress and cancer.

This led a team of researchers from University College London (UCL), the University of Edinburgh and the University of Sydney to analyse results on the subject from 16 studies. Thirteen of these had been carried out in England and three in Scotland.

In total, these involved 163,363 men and women aged 16 or older and were conducted between 1994 and 2008.

None of the participants had cancer when they were enrolled in the studies and all were assessed for symptoms of depression or anxiety. On average, they were monitored for nine-and-a-half years, during which time, 4,353 died from cancer.

The researchers discounted some factors that could have influenced cancer development, such as age, education, background, weight, smoking and alcohol consumption.

5 types of cancer

David Batty from UCL, who led the study, says in a statement: "After statistical control for these factors, 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."

Overall, those classified as the most depressed or anxious were 32% more likely to die of cancer than those in the least psychologically distressed group.

The results also revealed a link between increasing severity of depression and anxiety and increasing rates of cancer deaths.

The authors point out that the association may be partly explained by undiagnosed cases of cancer affecting some people's mood.

In an attempt to correct for this, they carried out a further analysis excluding study participants who died in the first 5 years of the studies. However, this made no difference and the links between psychological distress and cancer remained.

"Our findings contribute to the evidence that poor mental health might have some predictive capacity for certain physical diseases but we are a long way off from knowing if these relationships are truly causal," says David Batty.

More research needed

In an emailed statement, Professor Peter Johnson, Cancer Research UK’s chief clinician, comments: "This interesting study suggests a link between a person’s mental health [and] their risk of dying from cancer. But we need more research to see if this is really the case, or if anxiety and depression are linked to known cancer risks such as smoking, overweight and high alcohol intake.

"Better mental health may be another way in which we can reduce our risk of developing cancer, and this deserves serious attention."