Background. Many kinds of human malignant tissue, including hepatocellular carcinoma (HCC), were reported to overexpress transforming growth factor‐β1 (TGF‐β1) gene. However, little work has been done on the circulating TGF‐β1 in patients with malignant tumors.

Methods. Plasma TGF‐β1 levels in patients with HCC (n = 26) were compared with those in patients with chronic hepatitis (CH) (n = 12) and cirrhosis (n = 11) and in normal subjects (n = 20) using an enzyme‐linked immunosorbent assay system after acid/ethanol extraction.

Results. The patients with HCC had significantly higher plasma TGF‐β1 levels (19.3 ± 19.5 ng/ml; mean ± standard deviation [SD]) than those in normal subjects (1.4 ± 0.8 ng/ml) and in patients with CH (3.0 ± 3.1 ng/ml) and cirrhosis (3.7 ± 2.1 ng/ml) (P < 0.01). Plasma TGF‐β1 concentrations in the patients with cirrhosis were also significantly higher than those in the normal subjects (P < 0.05). The extracted plasma TGF‐β1 from the patients with HCC had biologic activity according to a growth inhibitory assay using mink lung epithelial cells. No significant correlation was found between the plasma TGF‐β1 levels in the patients with HCC and serum alpha‐feto‐protein levels. After successful treatment for HCC, the amount of plasma TGF‐β1 significantly decreased from 22.6 plus or minus 16.7 ng/ml (mean ± SD) to 10.2 plus or minus 6.5 ng/ml (P < 0.05).

Conclusions. We demonstrated higher levels of plasma TGF‐β1 in the patients with HCC than those in patients with chronic hepatitis and cirrhosis. Plasma TGF‐β1 might he a candidate for a novel tumor marker for hepatocellular carcinoma.