PC diagnosis was based on tumor markers, abdominal imaging, and/or histological findings, as described elsewhere [3 (link)]. The staging of PC was determined according to the clinical stage, except for stage 0, which was confirmed pathologically [11 (link)]. Since a nationwide survey of PC revealed significant differences in 5-year survival between stage IB (59.7%) and stage IIA (30.2%) [2 (link)], stages 0–IB were defined as early stages in this study, while stages IIA–IV were defined as non-early stages.
In this study, liver biopsy was considered the gold standard for diagnosing CLD. The aspartate aminotransferase-to-platelet ratio index (APRI) was calculated in patients with CLD. However, the final decision on the interval of HCC surveillance is made by individual hepatologists. Abdominal imaging (ultrasound, CT, MRI) and tumor markers analysis (AFP, DCP) were generally performed every three to four months in cirrhosis patients and every six months in non-cirrhosis patients, according to the guideline recommendations [10 (link)].
Data are reported as mean ± standard deviation or number and percentage. Intergroup comparisons were performed using the chi-squared test. Outcomes were analyzed using the Kaplan–Meier method and Cox proportional hazards regression. Differences in survival analyses were determined using the log-rank test. The differences were considered statistically significant at a two-tailed p-value < 0.05. All statistical analyses were performed using JMP software (version 13; SAS Institute, Cary, NC, USA). To ensure the anonymity of patient data, the data were stored in a secure database, and the patients were numerically coded. The study protocol complied with the ethical guidelines of the Declaration of Helsinki and was approved by the ethics committee of Ehime University Graduate School of Medicine (1204066). The requirement for written consent was waived owing to the study’s retrospective nature.