patient and her father
Photo by Rhoda Baer
A study published in The BMJ suggests that higher levels of psychological distress (anxiety and depression) may be associated with an increased risk of death from leukemia and other cancers.
The findings are observational, so no firm conclusions about cause and effect can be drawn.
However, the researchers said the findings add to the growing evidence that psychological distress could have some predictive capacity for certain physical conditions.
There is some evidence that psychological distress (anxiety and depression) is related to increased rates of cardiovascular disease, but links with different types of cancer are either unclear or untested.
So David Batty, PhD, of University College London in the UK, and his colleagues set out to examine if psychological distress is a potential predictor of site-specific cancer mortality.
The researchers analyzed data from 16 studies (13 from England and 3 from Scotland), which started between 1994 and 2008. The data included 163,363 men and women age 16 or over who were free from cancer at the start of the study.
Psychological distress scores were measured using the general health questionnaire (GHQ-12), and participants were monitored for an average of 9.5 years. During this time, there were 4353 deaths from cancer.
Several factors that could have influenced the results were taken into account, including age, sex, education, socioeconomic status, body mass index, smoking, and alcohol intake.
“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 esophagus and for leukemia,” Dr Batty said.
He and his colleagues pointed out that this association may also be affected by reverse causality, where undiagnosed (early) cancer might have had an underlying impact on mood.
In a bid to correct for this, the team conducted a further analysis excluding study participants who died in the first 5 years of follow-up, but this made no difference to the findings. The links between distress and cancer remained.
Specifically, compared to people in the least distressed group (GHQ-12 score 0-6), death rates in the most distressed group (score 7-12) were consistently increased for cancer of all sites combined, with a multivariable adjusted hazard ratio (HR) of 1.32.
Death rates were also increased for colorectal (HR=1.84), prostate (HR=2.42), pancreatic (HR=2.76), and esophageal cancers (HR=2.59), as well as for leukemia (HR=3.86).
“Our findings contribute to the evidence that poor mental health might have some predictive capacity for certain physical diseases,” Dr Batty said, “but we are a long way off from knowing if these relationships are truly causal.”
