Serum alpha-fetoprotein subfractions in patients with primary hepatoma or hepatic metastasis of gastric cancer.

Alpha-fetoprotein (AFP) subfractions were studied in 38 sera including 34 patients with primary hepatoma and 4 from patients with hepatic metastasis of gastric cancer. Fractionation of AFP was carried out by concanavalin A (Con A) or lentil lectin (LCH) crossed-line affinity immunoelectrophoresis. With use of Con A, fetal-liver-originated subfraction (peak a) was commonly found in both primary hepatoma and metastatic liver cancer, while yolk-sac-originated subfraction (peak b) was detected in 7 of 34 (20.6%) primary hepatomas and 4 of 4 (100%) metastatic liver cancers. With use of LCH, fetal-liver-originated subfractions (peaks A and/or C) were commonly found in both primary hepatoma and hepatic metastasis of gastric cancer, while yolk-sac-originated subfraction (peak B) was found only in metastatic liver cancer. These findings suggest that glycosylation of AFP in primary hepatoma differs from that in hepatic metastasis of gastric cancer. It is also suggested that AFP synthesized in hepatic cancers and fetal liver are differently glycosylated and AFP synthesis of hepatic malignancies are not always retrogenetically expressed, as in case of the fetal liver. Clinically, different patterns of AFP subfraction identified by Con A or LCH crossed-line affinity immunoelectrophoresis facilitate a differential diagnosis of primary hepatoma and hepatic metastasis of gastric cancer, in cases of elevated serum AFP levels. In the current study, attention was also given to the retrogenetic expression of AFP synthesis in hepatic metastasis of gastric cancer.