Tuberculosis and risk of cancer: a Danish nationwide cohort study

OBJECTIVES: To investigate the short- and long-term risk of cancer in patients with active tuberculosis (TB). DESIGN: Using Danish nationwide databases, we quantified cancer risk in TB patients during 19782011 compared with the general population. RESULTS: We observed 1747 cancers in 15 024 TB patients (median follow-up 8.5 years), reflecting a standardised incidence ratio (SIR) of 1.52 (95%CI 1.45-1.59). All-time SIR for extra-pulmonary cancer was 1.29 (95%CI 1.22-1.36) and for lung cancer it was 3.40 (95%CI 3.09-3.74). Absolute cancer risk 3 months after TB was 1.83% (SIR 11.09, 95%CI 9.82-12.48), with highly increased SIRs for malignant pleural mesothelioma (368.4), lung cancer (40.9), Hodgkin's lymphoma (30.6), ovarian cancer (26.4) and non-Hodgkin's malignant lymphoma (23.8). Between the 3-month and 5-year follow-up, the SIR for any cancer was 1.59 (95%CI 1.46-1.72), including 19- and 3-fold increases for malignant pleural mesothelioma and lung cancer. Beyond 5 years, the SIR of cancer was 1.17 (95%CI 1.10-1.25). Elevated long-term risks persisted for haematological (SIR 1.34, 95%CI 1.01-1.74) and tobacco-related cancers (SIR 1.78, 95%CI 1.60-1.97). CONCLUSION: TB is a marker of occult lung cancer and several extra-pulmonary cancers. TB also predicts increased long-term risk of cancer, possibly related to chronic inflammation and shared risk factors, including immunosuppression and smoking.