[AFP producing stomach cancer--a study of transplanted tumor in nude mice].

AFP producing cancer of the stomach was divided into 2 groups; Group A demonstrated a marked elevation of serum AFP levels before gastrectomy and was positive for AFP by PAP staining; group B showed delayed elevation of AFP levels at recurrence or in the terminal stage. Experimentally, we could establish three cell lines from group A and two lines from group B from transplanted tumor in nude mice. Tumor growth, changes of serum AFP levels and PAP staining investigated in each group. Group A and B were not only thought to exhibit different biological behavior, but also different mechanisms in AFP production. Group A cells may have the ability to secrete high levels of AFP; this may be a property of these tumor cells. On the other hand, group B tumor cells initially have little ability to secrete AFP. However, they may transform into AFP producing cells as a phenomenon of cell differentiation.