Plasma and peritoneal fluid levels of CA 125 in women with endometriosis.

Determined by a sandwich, solid-phase radioimmunoassay with mouse monoclonal antibody, OC 125, plasma CA 125 levels were significantly elevated in stage III (mean +/- SEM = 32.7 +/- 5.2 U/ml, n = 17, p = less than 0.01) and stage IV endometriosis (37.2 +/- 10.5 U/ml, n = 6, p = less than 0.005) compared with levels during the follicular (15.9 +/- 1.5 U/ml, n = 12) and secretory phases (15.8 +/- 1.3 U/ml, n = 15) of control women and users of oral contraceptives (15.5 +/- 1.2 U/ml n = 10). However, CA 125 levels were not significantly elevated in women with stage I (16.6 +/- 2.0 U/ml, n = 28) or stage II endometriosis (17.9 +/- 2.1 U/ml, n = 13). Peritoneal fluid levels of CA 125 (n = 14) were significantly higher (2 to 9.3 times) than the corresponding paired plasma levels in participants with stage I, II, or III endometriosis. In patients treated with danazol (n = 10) or buserelin (n = 17), plasma CA 125 levels decreased significantly by midtherapy, remained suppressed at the end of therapy, but rebounded to near pretreatment levels 6 months after treatment was completed. With gestrinone therapy a similar decline was observed but became significant only at the end of therapy. Our findings indicate that elevated plasma CA 125 levels may prove useful in the management of endometriosis.