The power of tumor sizes in predicting the survival of solitary hepatocellular carcinoma patients

Background: Vascular invasion, rather than tumor size, was applied into the 7th edition of the AJCC TNM staging system to predict survival of solitary hepatocellular carcinoma (HCC) patients. However, does this mean tumor size is of little value in prognostic prediction? The current study was designed to explore the prognostic ability of tumor sizes in solitary HCC. Methods: A total of 18 591 patients with solitary HCC categorized as T1 and T2 were retrieved from the Surveillance Epidemiology and End Results (SEER) database. The Cox proportional hazards regression model was adopted to evaluate the impact of tumor sizes on overall survival (OS) and disease-specific survival (DSS) in general and in subgroups stratified by vascular invasion and surgery type. Results: Large tumor sizes (>39 mm) were associated with unfavorable clinicopathologic characteristics. Compared with tumors ≤30 mm, tumors between 31-50 mm and tumors >50 mm showed significantly worse OS and DSS in general using multivariate analysis (all P < 0.001). In subgroup analyses, for patients without vascular invasion, tumor size was a notable prognostic indicator for OS in the radiofrequency ablation group (P < 0.001), rather than in the liver resection or transplantation group. Nevertheless, for patients with vascular invasion, tumor sizes exhibited a notable impact on OS in the liver resection and transplantation group. Conclusions: The AJCC TNM staging system for solitary HCC would be more comprehensive if tumor sizes were integrated into the T2 classification. Additionally, for T1 patients, tumor sizes play no role in the choice between resection and transplantation.