Cryptogenic pyogenic liver abscess as a sign of colorectal cancer: A population-based 5-year follow-up study

Background/aims: No large-scale population-based study has ever been conducted to examine the relationship between cryptogenic pyogenic liver abscesses (PLA) and the subsequent risk of colorectal cancer. This study aimed to estimate the risk for colorectal cancer following a diagnosis of cryptogenic PLA over a 5-year period. Methods: The study group comprised 274 patients who visited an outpatient care centre or were hospitalized with a diagnosis of cryptogenic PLA between 2001 and 2003. The comparison group included 1370 randomly selected subjects. Cox proportional hazard regressions were performed to compare the 5-year colorectal cancer-free survival rates for these two groups. Results: Of the total sample, 40 patients from the study group (2.43%) had colorectal cancer during the 5-year follow-up period: 15 (5.45% of those with cryptogenic PLA) and 25 from the comparison group (1.82% of the comparison group). After adjusting for patients' age, sex, monthly income, level of urbanization and geographical location, the hazard of colorectal cancer during the 5-year period was 3.36 times greater for patients with cryptogenic PLA than for the comparison group [95% confidence interval (CI)=1.72-6.56, P