Lithium not linked to increased cancer risk in patients with bipolar disorder
No difference was observed in risk of overall cancer in patients with bipolar disorder who use lithium, compared with the general population.
Patients with bipolar disorder who use lithium do not have an increased risk of cancer, according to a study published in Bipolar Disorders.
Lina Martinsson, MD, from the Clinic for Affecting Disorders in Stockholm, and colleagues conducted a nationwide study of incidence rate ratios of total cancer and site-specific cancer in patients with bipolar disorder. Recent studies have reported an increased risk of solid renal tumors among long-term lithium users.
Dr Martinsson's group included patients who were 50 to 84 years of age. The study was conducted from July 1, 2005, to December 31, 2009, and participants were evaluated with and without lithium treatment compared to the general population.
A total of 2,593,011 persons in the general population between 50 and 84 years were included; 2,393 patients had bipolar disorder and received lithium treatment, and 3,094 patients had bipolar disorder but did not receive lithium treatment. In patients with bipolar disorder, there were 327 (6.0%) cancer cases, compared with 166,443 (6.4%) in the general population. In patients with bipolar disorder with lithium treatment, there were 142 (5.9%) cancer cases, compared with 185 (6.0%) in those without lithium treatment.
No difference was observed in risk of overall cancer in patients with bipolar disorder with lithium treatment compared with the general population (risk ratio, 1.04), nor in patients with bipolar disorder without lithium treatment compared with the general population (risk ratio, 1.03).
The cancer risk was significantly increased in digestive organs in patients with bipolar disorder without lithium treatment (risk ratio, 1.47), but there was no increase in patients who used lithium compared with the general population (risk ratio, 1.34). A significant cancer risk was observed in the respiratory system and intrathoracic organs (risk ratio, 1.72) and in the endocrine glands (risk ratio, 2.60) in patients with bipolar disorder without lithium treatment.
“The main finding of the study was that lithium treatment was not associated with the overall cancer risk in Swedish patients with bipolar disorder in the age group 50-84 years,” the authors stated. “Furthermore, lithium treatment resulted in no significant increase in cancer risk in any site-specific cancer type.”
- Martinsson L, Westman J, Hällgren J, Ösby U, Backlund L. Lithium treatment and cancer incidence in bipolar disorder. Bipolar Disord. February 2016. doi: 10.1111/bdi.12361.