Extrahepatic metastasis of hepatocellular carcinoma: incidence and risk factors

Background: Extrahepatic metastasis of hepatocellular carcinoma (HCC) is of growing importance as the survival of patients has been improved owing to advances in treatments to intrahepatic lesions. Methods: To elucidate the incidence and risk factors of extrahepatic metastasis of HCC, we enrolled 1573 (1131 treatment-naive and 442 previously treated on referral) patients with HCC without extrahepatic tumour spread treated at the authors' department between 1990 and 2003. Patients received medical treatment including percutaneous ablation and transcatheter arterial chemoembolization, and followed by dynamic computed tomography (CT) or magnetic resonance imaging (MRI) and tumour markers every 3-4 months. Extrahepatic metastasis was diagnosed by plain X-ray, CT, MRI and scintigraphy. Clinical parameters at the time of treatment to intrahepatic lesions were evaluated as a predictor of subsequent extrahepatic metastasis among the 1131 treatment-naive patients by Cox's proportional hazard model. Results: During the average observation period of 3.9 years, extrahepatic metastasis was diagnosed in 123 in the treatment-naive and 53 in the patients treated previously. The incidence rate of extrahepatic metastasis, as detected during the lifetime after medical treatment of HCC, was approximately 13% at 5 years. Multivariate analysis with Cox proportional hazard model revealed that positivity for viral markers, lager tumour diameter, multiple tumour nodules, presence of vascular tumour invasion and elevated tumour markers were associated with the development of extrahepatic metastasis. Conclusions: The incidence of extrahepatic metastasis of HCC diagnosed during clinical course was not frequent. Advanced intrahepatic lesions, presence of vascular tumour invasion, elevated tumour markers and presence of viral hepatitis were risk factors for extrahepatic metastasis.