Cancer Risk in Patients With Empyema: A Nationwide Population-Based Study

This study aimed to evaluate cancer risk and possible risk factors in patients diagnosed with empyema. A total of 31,636 patients with newly diagnosed empyema between January 1, 1999 and December 31, 2010 were included in this study. Standardized incidence ratios (SIRs) were calculated to compare the cancer incidence in these empyema patients to that in the general population. Adjusted hazard ratios were also calculated to investigate whether characteristics increased cancer risk. During the 12-year study period, 2,654 cancers occurred in 31,636 patients with empyema, yielding an SIR of 2.67 (95% confidence interval [CI] 2.57-2.78). We excluded cancer that occurred within 1 year to avoid surveillance bias. The cancer risk remained significantly increased (SIR 1.50, 95% CI 1.41-1.58). Specifically, patients with empyema had higher SIR of cancers of the head and neck (1.50, 95% CI 1.41-1.58), esophagus (2.56, 95% CI 1.92-3.33), stomach (1.49, 95% CI 1.16-1.89), liver and biliary tract (2.18, 95% CI 1.93-2.45), and lung and mediastinum (1.62, 95% CI 1.39-1.86). Age ≥ 60, male sex, diabetes mellitus, and liver cirrhosis were independent risk factors for cancer development. Our study demonstrates an increased incidence of cancer development in patients with empyema, and patients' age ≥ 60, men, and those with diabetes mellitus and liver cirrhosis showed a higher incidence of developing cancer compared to the general population. The association between such kind of infection and secondary malignancy may be elucidated by further study.