Serum CA 125 levels before, during and after treatment for endometriosis.

OBJECTIVES The aim of this study was to assess the treatment of endometriosis with a gonadotropin-releasing hormone (GnRH) agonist in terms of changes to the extent of disease and to CA 125 levels as well as to recurrence during follow-up. METHODS The levels of serum CA 125 were evaluated in 66 patients with endometriosis diagnosed and staged by laparoscopy according to the revised American Fertility. Society classification, who received a 6-month course of a GnRH agonist. Serum CA 125 levels were measured before, during (3 and 6 months after the initiation of therapy) and 6 months after cessation of therapy. RESULTS Patients with minimal and mild endometriosis had significantly higher mean pretreatment values than control subjects in the luteal phase of the cycle or than postmenopausal women (P < 0.05), but the overall mean value was still below 35 U/ml. Levels of CA 125 fell during treatment to those found in normal controls, but rose again after the end of treatment. The sensitivity and specificity of CA 125 were 75% and 83.3%, respectively, and its positive predictive value as a marker of recurrence was 46.36%. CONCLUSION These data suggest that CA 125 may be a reliable indicator for monitoring the efficacy of GnRH agonist treatment of endometriosis, but its value as a predictor of recurrence is low, probably due to the suppression of all CA 125 sources such as endometrium, ovaries and implants.