Abstract
Thirteen women with adenocarcinoma of the endometrium were treated with standardized doses of hydroxyprogesterone caproate for 3 weeks. Histological and histochemical studies of tumour tissue were performed before and after the treatment. Most of the well differentiated carcinomas showed secretory and acantho-matous changes after the treatment, whereas such changes were more rarely seen in tumours with low degree of differentiation. There was a great variability in the enzyme pattern. Alkaline phosphatase activity seemed to decrease during the treatment, whereas acid phosphatase and adenosine triphosphatase activities were mostly unaffected. The serum levels of LH decreased, whereas the plasma level of corticoids and the urinary excretion of oestriol and pregnandiol showed no definite changes during the treatment.