Incidence of needle tract seeding and responses of soft tissue metastasis by hepatocellular carcinoma postradiotherapy

Aim: To determine the incidence of needle tract seeding after fine needle aspiration (FNA) or percutaneous ethanol injection (PEI) and compare iatrogenic or spontaneous soft tissue metastasis (STM) by hepatocellular carcinoma (HCC) postradiotherapy (RT) in responses. Methods: From November 1997 to January 2006, those who presented with STM by HCC after our invasive procedures or developed spontaneously were enrolled into this retrospective study. Metastatic lesions could be divided into procedure related (PR), which were located at the liver span and were related to invasive procedures, and non-procedure related (NPR), which were in extrahepatic areas. STM was treated with an electron or photon beam. Results: A total of 39 HCC cases with developed STM were referred for RT, including 17 in the PR group and 22 in the NPR group. During the same period, a total of 18 227 person-times of FNA or PEI were performed on these HCC patients. The overall incidence of HCC with STM that was caused by invasive procedures was estimated at 0.13%. According to the Cox' regression model, the initial treatment modality influences the time duration after the initial diagnosis of HCC when STM has not occurred. None of these patients' soft tissue tumor increased in size during RT. The PR group had lower rates of bone metastasis (P=0.003) and coexisting extrahepatic metastasis (P=0.011) and a longer survival rate (P=0.003) than the NPR group. The estimated rates of 18-gauge and 22-gauge needle-induced HCC-related STM were 0.60% and 0.11%, respectively (P=0.064). Conclusion: The PR group bears a better prognosis than the NPR group post-RT.