Depression, Fatigue Not Linked to Cancer

"Vital exhaustion" - the energy-draining combination of depression and fatigue - does not increase the risk of cancer, according to a large prospective study from Denmark. Although people who reported the most vital exhaustion exercised less and smoked more than their more energetic peers, they were still not at increased risk for any cancer, according to a study reported in the August 8 online edition of Cancer.

"We deduce that there is neither a direct positive influence of vital exhaustion on cancer risk via an immune mechanism nor an indirect association promoted by unhealthy life style factors," wrote the authors from the Danish Cancer Society in Copenhagen.

The researchers investigated the possibility of a cancer link after discovering that vital exhaustion increased risk for heart attacks and all-cause mortality. With questionnaire results from 8,500 people already in hand through the long-running Copenhagen City Heart Study, the authors linked the results to the Danish Cancer Registry, which records every diagnosis in the country of 5.4 million people. The questionnaires completed from 1991 to 1994 and the cancer data collected in 2002 resulted in a mean follow-up time of 8.6 years.

The authors cautioned that selection bias could have been at play - that is, the most eager study participants tended to be the healthiest. Only 61 percent of the original heart study participants completed the exhaustion questionnaire.