"Depression is related to a slightly increased risk of cancer," investigator Dr Marjan van den Akker told Reuters Health. "The relation with breast cancer gets stronger with a longer follow-up period."
Van den Akker, of Maastricht University, and colleagues came to this conclusion after examining data from 13 studies involving more than 127,000 patients. Their findings are published in the journal Clinical Practice and Epidemiology in Mental Health.
Risk increase by 12 percent
Based on eight studies with complete data, the researchers calculated that the overall risk of cancer was increased by 12 percent in individuals with depression.
Based on data from seven studies that looked at a mixture of factors, no significant association was seen between depression and the development of breast cancer.
However, analysis of a subgroup of studies that included at least 10 years of follow-up showed a significant association - patients with depression had a 2.5-fold increased risk of developing breast cancer compared with patients who are not depressed.
"With the evidence available at this moment, it's difficult to disentangle the possible effects of depression and antidepressants on the occurrence of subsequent cancer," continued Van den Akker. "It's not yet possible to translate these results into preventive interventions," she concluded. - (David Douglas/Reuters Health)
SOURCE: Clinical Practice and Epidemiology in Mental Health, December 3, 2007.