Use of lithium and cancer risk in patients with bipolar disorder: population-based cohort study

Background Lithium inhibits glycogen synthase kinase-3, which is an enzyme involved in the pathogenesis of cancer. Aims To investigate the association between lithium and cancer risk in patients with bipolar disorder. Method A retrospective cohort study was designed using the National Health Insurance Research Database (NHIRD) in Taiwan. Patients using lithium comprised the index drug group and patients using anticonvulsants only comprised the control group. Time-dependent Cox regression was used to evaluate the hazard ratios (HRs) for risk of cancer. Results Compared with anticonvulsant-only exposure, lithium exposure was associated with significantly lower cancer risk (HR=0.735, 95% Cl 0.554-0.974). The hazard ratios for the first, second and third tertiles of the cumulative defined daily dose were 0.762 (95% Cl 0.516-1.125), 0.919 (95% Cl 0.640-1.318) and 0.552 (95% Cl 0.367-0.831), respectively. Conclusions Lithium is associated with reduced overall cancer risk in patients with bipolar disorder. A dose response relationship for cancer risk reduction was observed. (C) The Royal College of Psychiatrists 2016.