Solid-organ malignancy as a risk factor for tuberculosis

Background and objective: The effective control of tuberculosis (TB) requires that people at high risk for the reactivation of TB are identified. Haematological malignancy has been shown to be a risk factor for the development of TB, either through immune suppression by the tumour or through the effects of chemotherapy. This study assessed the hypothesis that solid-organ malignancy is a risk factor for the development of TB. Methods: A retrospective cohort study was performed to determine the incidence of TB in patients with solid-organ malignancy and in control subjects without malignancy. Risk factors for the development of TB among patients with cancer were also assessed. Results: The study recruited 1809 cases with cancer and 1809 control subjects and followed them for 3 years. The incidence of active TB per 1000 person-years was 3.07 in patients with cancer and 0.77 in controls (P = 0.009). Compared with the control group, patients with cancer had an increased risk of developing TB (incidence rate ratio (IRR) 4.69, 95% CI: 1.52-14.46). Proportional hazards regression analysis showed that the risk factors for development of TB were chronic renal failure (IRR 9.91, 95% CI: 1.17-83.60), old healed TB on CXR (IRR 45.05, 95% CI: 5.74-353.88), and anticancer chemotherapy (IRR 4.32, 95% CI: 1.10-16.89). An interaction between old healed TB and anticancer chemotherapy was observed. Conclusion: These findings indicate that immune suppression by cancer or by anticancer chemotherapy increases vulnerability to reactivation of TB, especially in cancer patients with old healed TB.