Use of sleep medications and risk of cancer: a matched case-control study

Previous research suggests a possible link between sleep-medication use and mortality, especially cancer deaths, but findings are mixed, and large population-based studies are lacking.

Data from the Finnish Public Sector study were linked to the Finnish Cancer Register and the Drug Prescription Register of Finland. A total of 5053 cancer cases (mean age of 57.4 years) diagnosed in 2002-2011, and their 24,388 controls free of cancer and matched for sex, age, socioeconomic status, employer, and geographical area, were identified. The use of sleep medications was defined as purchases of prescribed sleep medications.

Both quantity and duration of prior sleep-medication use during the seven years studied were associated with increased odds of having cancer. Compared with participants not using sleep medications, the odds ratio was 1.18-fold (95% confidence interval (CI): 1.01-1.39) for those who used >100 defined daily doses per year and 1.16-fold (95% CI: 1.01-1.34) for those who had such a medication for >3 years. Site-specific analyses showed a more pronounced association of quantity and duration of sleep-medication use with subsequent cancer of the respiratory system (odds ratio for >100 defined daily doses per year vs. no use: 3.47; 95% CI: 1.97-6.11). No associations were found with other cancer sites.

In this register-based study, sleep-medication use was associated with an increased cancer incidence of the respiratory system. Further studies are needed to examine potential carcinogenic mechanisms associated with hypnotic medications.