Risk of tuberculosis in patients with cancer treated with immune checkpoint inhibitors: a nationwide observational study

Background While some recent studies have reported the development of tuberculosis (TB) in patients exposed to immune checkpoint inhibitors (ICIs), there is limited evidence to date. Therefore, we evaluated the risk of TB in patients with cancer exposed to ICIs using the National Health Insurance claims data in South Korea. Methods Patients with diagnostic codes for non-small cell lung cancer, urothelial carcinoma or melanoma between August 2017 and June 2019 were identified. The incidence rate and standardized incidence ratio (SIR) of TB were calculated for both the ICI exposure and non-exposure groups. The risk of TB according to ICI exposure was assessed using a multivariable Cox regression model. Results During the study period, 141 550 patients with cancer and 916 new TB cases were identified. Among the 5037 patients exposed to ICIs, 20 were diagnosed with TB at a median of 2.2 months after the ICI was initiated. The crude incidence rate of TB per 100,000 person-years was 675.8 (95% CI 412.8 to 1043.8) for the ICI exposure group and 599.1 (95% CI 560.5 to 639.6) for the non-exposure group. The SIR for TB was 8.1 (95% CI 8.0 to 8.2) in the ICI exposure group. After adjusting for potential confounding factors, ICI treatment was not significantly associated with an increased risk of TB (HR: 0.73; 95% CI 0.47 to 1.14). Conclusions While the incidence of TB in cancer patients exposed to ICIs was eightfold higher than in the general population, the risk of patients with cancer developing TB did not significantly differ according to ICI exposure.