Cancer morbidity in psychiatric patients: influence of lithium carbonate treatment.

The relationship between mental diseases and cancer development has been examined in a number of studies but the findings are still inconclusive and suffer from methodological problems. Studies conducted to examine the effect of lithium on malignant cells yielded inconsistent results. The study group included 609 patients treated by lithium carbonate and 2396 controls. A lower but non significant risk (RR = 0.79; CI = 0.17-3.60) to develop non-epithelial tumors was found among lithium carbonate treated psychiatric patients as compared to controls. A significantly (P = 0.05) inverse trend of cancer with lithium dose was observed. The risk of cancer development among each group of psychiatric patients was significantly lower than in the general population (RR = 0.68 for the lithium treated group versus 0.78 for controls). Mental patients have a lower cancer prevalence than the general population and lithium may have a protective effect.