Solid-organ malignancy as a risk factor for tuberculosis

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.

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.

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.

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.