Unexpected increase of the CA 19-9 tumour marker in patients with endometriosis

The purpose of this study was to investigate whether the ovarian function of women with endometriosis could be identified by serologic concentration of the oncofetal antigen CA 19-9 before, during and after treatment for 6 months with danazol. A total of 15 women with endometriosis, 20-40 years old, were studied. The serum CA 19-9 antigen was measured by immunoradiometric assay. The measurement of CA 19-9 was repeated during the last 15 days of a 6-month therapy period with danazol and after 3 months from the end of the therapy in only seven women. It was found that: 1) Eight out of 15 women (53.3%) showed higher CA 19-9 values than the upper normal limit. 2) Danazol caused a significant decrease in the antigen values which remained stable after the cessation of therapy. This data suggests that endometriosis should be classified among other diseases which cause an increase in the serum levels of CA 19-9 and that ovarian function is related to antigen levels.