Depression can affect a cancer patient's likelihood of survival. That is the finding of an analysis published in the November 15, 2009 issue of CANCER, a peer-reviewed journal of the American Cancer Society. The results highlight the need for systematic screening of psychological distress and subsequent treatments.

A number of studies have shown that individuals' mental attitudes can impact their physical health. To determine the effects of depression on cancer patients' disease progression and survival, graduate student Jillian Satin, MA, of the University of British Columbia in Vancouver, Canada, and her colleagues analyzed all of the studies to date they could identify related to the topic.

The researchers found 26 studies with a total of 9417 patients that examined the effects of depression on patients' cancer progression and survival.

"We found an increased risk of death in patients who report more depressive symptoms than others and also in patients who have been diagnosed with a depressive disorder compared to patients who have not," said Satin. In the combined studies, the death rates were up to 25 percent higher in patients experiencing depressive symptoms and 39 percent higher in patients diagnosed with major or minor depression.

The increased risks remained even after considering patients' other clinical characteristics that might affect survival, indicating that depression may actually play a part in shortening survival. However, the authors say additional research must be conducted before any conclusions can be reached. The authors add that their analysis combined results across different tumor types, so future studies should look at the effects of depression on different kinds of cancer.

The investigators note that the actual risk of death associated with depression in cancer patients is still small, so patients should not feel that they must maintain a positive attitude to beat their disease. Nevertheless, the study indicates that it is important for physicians to regularly screen cancer patients for depression and to provide appropriate treatments.

The researchers did not find a clear association between depression and cancer progression, although only three studies were available for analysis.