In vitro CA-125 secretion by endometrium from women with advanced endometriosis

OBJECTIVE: To determine if the endometrium of women with endometriosis is a potential source of the elevated serum concentrations of CA-125 associated with endometriosis. DESIGN: Secretion of CA-125 by the endometrium in tissue culture was documented and measured in response to treatment with progesterone (P), 17 beta-estradiol (E2), and progesterone and estradiol (E2+P). Sequential biopsies of the endometrium from the early and late luteal phase were obtained from women with laparoscopically documented normal anatomy or moderate to severe endometriosis. SETTING: Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology at the University of Vermont, College of Medicine, Burlington, Vermont. MAIN OUTCOME MEASURES: Secretion of CA-125 by endometrium in vitro was determined by radioimmunoassay in spent media using a commercially available kit (Centicor CA-125 Kit; Centicor, Malvern, PA). RESULTS: Secretion of CA-125 by endometrium in vitro is inhibited by the presence of P and E2+P in both the early and the late luteal phase. The amount of CA-125 secreted increases significantly from the early to the late luteal phase in all treatment groups. When compared with controls, the endometrium of women of with endometriosis secreted two to four times more CA-125 in all treatment groups, in both the early and late luteal phase. CONCLUSIONS: When compared with control endometrium, the endometrium of women with advanced endometriosis secretes significantly more CA-125 and represents a potential source of the elevated serum levels of CA-125 seen in these women.