Cancer risk in patients with pyogenic liver abscess: a nationwide cohort study

Background There has been no large-scale population-based study on the relationship between pyogenic liver abscesses (PLA) and subsequent cancer risk. Aim To estimate all cancer risk following a diagnosis of PLA. Methods Based on Taiwan's National Health Insurance Research Database, 1257 patients with PLA without prior cancers in the period 1996-2008 were identified and followed-up. The standard incidence ratio (SIR) of each cancer was calculated as the number of observed cancer cases arising among the PLA patients divided by the expected case number of cancer cases according to the national cancer rates. Results Of the 1257 PLA patients identified, 598 (47.6%) had diabetes mellitus. After a median (+/- s.d.) follow-up of 3.33 +/- 3.45 years, 186 were diagnosed with cancers, including 56 liver cancer, 22 biliary tract cancer and 40 colorectal cancer patients. Patients with PLA had a higher risk of all cancers (SIR, 3.83; 95% CI, 3.30-4.42), liver cancer (SIR, 7.87; 95% CI, 5.94-10.21), biliary tract cancer (SIR, 34.58; 95% CI, 21.67-52.36) and colorectal cancer (SIR, 5.27; 95% CI, 3.767.18). The highest SIRs of all cancers, liver cancer, biliary tract cancer and colorectal cancer occurred within 90 days of follow-up (360.82; 95% CI, 278.46-459.91, 257.28; 95% CI, 186.17-346.56, 1153.38; 95% CI 694.08-1801.24, and 52.63; 95% CI 25.296.8 respectively). Conclusions Pyogenic liver abscesses may herald the onset of cancer, especially hepato-biliary and colon cancer. Further surveys should be conducted for the detection of occult cancers in such patients.