Placenta-like alkaline phosphatase in gynecological cancers.

In 302 patients with tumors of the cervix, corpus uteri, and ovaries, assessment by clinical staging (tumors-nodules-metastasis system) (4) and histopathology has been related to the presence of serum heat-stable, placenta-lide alkaline phosphatase (PLAP) activity. Early stages of cervical tumors show the highest incidence of this isoenzyme. In advanced stages of this disease, a decrease in frequency was observed that might be interpreted as the result of gradual dedifferentiation of the tumor cells to a point where synthesis of PLAP became undetectable. The same observation was made in adenocarcinomas of the corpus uteri, i.e., patients with advanced disease tended to have the lowest incidence of serum PLAP. Only in cancers of the ovaries did we find a positive correlation between this enzyme marker and the extent of the disease. In more than one-third of the patients examined, PLAP levels were an index of the tumor burden.