[Histochemical studies on alkaline phosphatase in normal endometrium and endometrial carcinoma--with a special reference to heat stability and L-phenylalanine inhibition tests (author's transl)].

We report a histochemical study of alkaline phosphatase (ALP) in normal cells of uterine endometrium and endometrial cancer to ascertain the incidence of ALP and the isoenzyme type. For this purpose, cytological specimens and tissue serial sections were subjected to heat-stability and L-phenylalanine (L-p) inhibition test. The Regan-like isoenzyme, a heat-stable and L-p sensitive ALP, which had been thought to derive only from cancer or the placenta, was found in very limited endometrial luminal surface lining cells. Meanwhile ALP activity in endometrial glandular cells was heat and L-p sensitive. Of 42 cases of endometrial cancer, all cases manifested non-specific ALP activity, and 19 cases (45%) manifested heat stability of slight to high degree. 7 endometrial cancers exhibited the Regan-like isoenzyme with marked heat and L-p sensitivity. These findings indicate that in the course of uterine endometrial carcinogenesis, the ALP isoenzyme of endometrial glandular cells undergo a change and that "enzyme deviation" occurs.