Long-Term Glucocorticoid Use and Cancer Risk: A Population-Based Cohort Study in South Korea

Long-term glucocorticoid (GC) exposure causes immunosuppression; therefore, the risk of cancer may be increased in long-term GC users. We investigated whether long-term GC use is associated with a higher risk of cancer in the population without cancer. A population-based cohort study using data from the National Health Insurance Service was conducted among the South Korean adult population in 2010. Long-term GC users were defined as those who were prescribed a continuous supply of oral GC for ≥30 days. The primary endpoint was a new cancer diagnosis from January 1, 2011, to December 31, 2015. Among 770,880 individuals included in the analysis, 1,602 (0.2%) were long-term GC users and 36,157 (4.7%) were newly diagnosed with cancer from January 2011 to December 2015. In the multivariable Cox regression analysis, the risk of cancer among long-term GC users was 1.23-fold higher than that of the unexposed individuals [95% confidence interval (CI), 1.06-1.43; P = 0.007]. In the competing risk analyses, the risks of liver cancer and lung cancer were 1.46-fold (95% CI, 1.03-2.07; P = 0.034) and 1.52-fold (95% CI, 1.04-2.21; P = 0.029) higher in the long-term GC users than that of the unexposed individuals, respectively. We found that long-term GC exposure might be associated with a higher risk of overall cancer, and this association was more evident for lung and liver cancer risk. However, because there might be unmeasured and potential confounders in this study, the results should be interpreted carefully, and future studies should be performed to confirm these findings. IMPACT: Long-term glucocorticoid therapy might be associated with a higher cancer risk. This association was more evident for lung and liver cancer risk. Our findings suggest that long-term prescriptions of glucocorticoids should be administered carefully considering the risk of cancer.