The survival rates of cancer patients can be affected by depression, according to University of British Columbia researchers. To determine the effects of depression on cancer patients' disease progression and survival, UBC psychology graduate student Jillian Satin and colleagues analyzed 26 studies they could identify related to the topic.

The UBC researchers found 9,417 patients in the studies that examined the effects of depression on patients' cancer progression and survival and their analysis was published online Monday by the American Cancer Society journal Cancer.

"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 UBC release Monday.In the combined studies, the death rates were as much as 25 per cent higher in patients with depressive symptoms and 39 per cent higher in patients diagnosed with major or minor depression.

The increased risks remained even after considering other clinical characteristics that might affect survival, indicating that depression may actually play a part in shortening survival. However, the authors say in the release that additional research must be conducted before any conclusions can be reached.

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. The researchers didn't find a clear relation between depression and cancer progression, although only three studies were available to check.