Reduced Risk of Melanoma Associated With Lithium Use

A possible role for lithium in reducing an individual’s risk for melanoma and decreasing melanoma-specific mortality has been suggested by researchers, according to the results of a recent study published in the Journal of Investigative Dermatology.

The researchers conducted a retrospective cohort study of adult white Kaiser Permanente Northern California members between 1999 and 2012 to investigate the relationship between lithium use and melanoma risk. Of the 2,213,848 cohort members, a total of 11,317 individuals received lithium therapy and 14,056 were diagnosed with incident melanoma through the use of an established cancer registry. Lithium exposure in the 11,317 patients was assessed from pharmacy databases, and serum lithium levels were obtained from electronic laboratory databases. The average numbers of years of follow-up per cohort member was 6.9±5.4 years.

Lithium-exposed individuals were more likely to be younger (mean age, 41.0±14.8 years vs 42.5 ± 18.2 years for unexposed individuals; P <.001) and to be women (61.1% vs 54.4%, respectively; P <.001). Moreover, most of the exposed cohort members entered the group in earlier time periods compared with the unexposed members.          

The incidence of melanoma per 1000 person-years among lithium-exposed participants was significantly lower, at 67.4, as opposed to 92.5 among nonexposed individuals (P =.027). Additionally, lithium-exposed participants had a 32% decreased risk for melanoma in unadjusted analysis (hazard ratio [HR], 0.68; 95% CI, 0.51-0.90). This estimate was attenuated and nonsignificant in adjusted analysis, however (adjusted HR 0.77; 95% CI, 0.58-1.02).

None of the lithium-exposed participants presented with thick (>4 mm) or advanced-stage melanoma at diagnosis. Of the patients with melanoma, lithium-exposed persons were less likely than unexposed individuals to experience melanoma-associated death (4.68 per 1000 person-years vs 7.21 per 1000 person-years, respectively).    

The findings of this analysis demonstrate that lithium may decrease melanoma risk and associated mortality. “Our conclusions provide evidence that lithium, a relatively inexpensive and readily available drug, warrants further study in melanoma,” the researchers concluded.

Reference

Asgari MM, Chien AJ, Tsai AL, Fireman B, Quesenberry CP Jr. Association between lithium use and melanoma risk and mortality: a population-based study. J Invest Dermatol. 2017;137(10):2087-2091.