Circulating AFP mRNA as a Possible Indicator of Hematogenous Spread of HCC Cells: A Possible Association with HBV Infection.

BACKGROUND Circulating alpha fetoprotein messenger RNA (AFP mRNA) has been proposed as a marker of hepatocellular carcinoma (HCC) cells disseminated into the circulation. The specificity of this molecular marker and its correlation with the main HCC clinico-pathological parameters remains controversial. AIM This case control pilot study has been undertaken to detect the expression of human AFP mRNA in the peripheral blood of patients with HCC and liver cirrhosis (LC), to evaluate its clinical implication and to clarify its relationship with some clinico-pathologic characteristics in HCC. METHODS Peripheral blood (PB) samples were obtained from 32 patients with HCC (14 patients before treatment and 18 patients after treatment), 15 patients with LC and 10 normal donors. HCC patients with clinically evident extra-hepatic metastasis were excluded. AFP mRNA was amplified from the total RNA extracted from the whole blood by nested reverse transcription-polymerase chain reaction (RT-PCR). RESULTS Circulating AFP mRNA was positive in 25% (8/32) of all HCC patients, 42.9% (6/14) of patients before treatment, 11.1% (2/18) of patients previously treated, and 13.3% (2/15) of patients with liver cirrhosis without HCC. Circulating AFP mRNA detection rate was significantly higher in untreated than in treated HCC patients (p=0.04). There was no significant difference among the other various patient groups (LC Vs HCC all: p=0.31; LC Vs untreated HCC; p=0.11; LC Vs treated HCC; p=1.0). Both patients who tested positive for circulating AFP mRNA in the treated HCC group were in the chemoembolization subgroup (2/8=25%). None (0/5=0%) of post resection as well as radiofrequency subgroups of patients tested positive for circulating AFP mRNA. None of the normal controls tested positive for circulating AFP mRNA. The only variable associated with the presence of circulating AFP mRNA in HCC patients was being hepatitis B positive: 87.5% (7/8) of AFP mRNA positive HCC patients had had clinical evidence of chronic hepatitis B virus (HBV) infection (p=0.01, OR=14, 95% CI=1.46-134.25). None of the other variables (age, sex, HCV infection, Child-Pugh score, liver function indices, serum AFP values and tumor size) was significantly related to the presence of AFP mRNA in HCC patients. No patient with chronic liver disease (CLD) due to HBV infection tested positive for circulating AFP mRNA. CONCLUSION Using nested RT-PCR assay, circulating AFP mRNA could be detected in HCC patients without clinical evidence of extra-hepatic metastasis as well as in patients with LC. Although the possibility of hematogenous spread of HCC cells cannot be excluded, AFP mRNA expression in blood does not necessarily distinguish between circulating HCC cells and noncancerous hepatocytes. Although this is a small sample size pilot study, our findings imply that HBV infection may be an important contributing factor to the hematogenous spread of HCC cells. HBV infection was strongly associated with AFP mRNA expression in blood of HCC patients. Thorough investigation of this association in a larger series with HBV infection is needed. Also, another larger treated HCC series is needed for the assessment of AFP mRNA expression in blood in relation to specified treatment approaches. Key Words: AFP mRNA , Hepatocellular carcinoma (HCC) , RT-PCR , Chronic liver disease (CLD).