Association of alpha-fetoprotein and metastasis for small hepatocellular carcinoma: A propensity-matched analysis

Metastasis is crucial for the prognosis of hepatocellular carcinoma (HCC). Distinguishing the potential risk factors for distant metastasis in small HCC (diameter ≤ 5 cm) is of great significance for improving the prognosis. HCC patients in the Surveillance, Epidemiology and End Results (SEER) registry with tumors ≤ 5 cm in diameter between January 2010 and December 2015 were retrieved. Demographic and clinicopathological metrics were extracted, including age, sex, race, marital status, tumor size, histological grade, T stage, N stage, M stage, alpha-fetoprotein (AFP), and liver fibrosis score. Univariate and multivariate logistic regression analyses were used to identify independent risk factors correlated with extrahepatic metastasis in small HCC. Propensity score matching (PSM) analysis was performed to balance the confounding factors in baseline characteristics. A total of 4176 eligible patients were divided into a non-metastasis group (n = 4033) and a metastasis group (n = 143) based on metastasis status. In multivariate analysis, larger tumor size, poor histological differentiation, regional lymph node metastasis, and elevated serum AFP levels were identified as independent risk factors for distant metastasis (P < 0.05), while age, sex, race, marital status, and liver fibrosis score were not associated with extrahepatic metastasis. After propensity score analysis, the AFP level was no longer associated with metastatic risk. The present study provided no evidence for a correlation between the clinical threshold of AFP and metastasis in small hepatocellular carcinoma.