Serum progesterone and serum human chorionic gonadotropin in gestational and nongestational choriocarcinoma

Serum progesterone was assayed by the competitive protein-binding technique in 20 cases of gestational choriocarcinoma and one case of nongestational choriocarcinoma. Serum human chorionic gonadotropin (HCG) was simultaneously measured from the same blood samples by the hemagglutination-inhibition technique. Serum progesterone in choriocarcinoma ranged from 1.3 to 182.9 ng. per milliliter with a mean +/- standard error of the mean of 36.2 +/- 10.2 ng. per milliliter. Serum HCG ranged from 0.6 to 1,280 I. U. per milliliter. In 11 patients with choriocarcinoma, serum progesterone levels were indistinguishable from values obtained during the luteal phase of the normal menstrual cycle; six patients had values similar to those found in early normal pregnancy and four patients with postmolar villous choriocarcinoma had elevated serum progesterone. There was a significant correlation between serum HCG and serum progesterone (r = + 0.5652, p = 0.005). The significance of these findings is discussed with reference to the likely source of progesterone in choriocarcinoma.