Active tuberculosis risk associated with malignancies: an 18-year retrospective cohort study in Korea

Background: Active tuberculosis (TB) develops in approximately 10% of people with a latent tuberculosis infection (LTBI). TB guidelines recommend that LTBI screening and treatments target high-risk patients. Malignancies are not universally considered a high-risk factor for active TB. This study aimed to determine the degrees to which active TB risk was associated with various cancers in a Korean population. Methods: This study involved patients aged >= 20 years who were diagnosed with cancer at Ulsan University Hospital (UUH) from January 2000 to December 2014 and individuals who visited UUEI for health screening and were age- and sex-matched randomly with cases in a 1:2 ratio. Using retrospective cohort study, the development of bacteriologically con firmed TB (BCTB) within 3 years after enrollment was investigated. The relative risks of BCTB were estimated using incidence rate ratios (IRRs) and a Poisson regression analysis. Results: During the study period, 380 of 34,783 cancer patients and 79 of 69,566 control subjects developed BCTB, yielding respective incidence rates of 535 and 37/100,000 person-years, respectively. In all cancer cases, the IRR of BCTB was 14.30, and especially high rates were associated with the following cancers: esophageal cancer (74.72), multiple myeloma (70.76), lung cancer (50.35), pancreatic cancer (46.04), leukemia (40.45), head and neck cancer (24.60), and lymphoma (22.67). Conclusions: The incidence of active TB was higher in cancer patients than in control subjects. In particular, lung cancer, esophageal cancer, pancreatic cancer, hematologic malignancy and head and neck cancer were identified as high-risk factors for active TB, as indicated by IRRs of 20-75. These findings suggest that patients with high-risk cancers should be targeted for LTBI screening and treatment.