Comparison of standard and CA-125 response criteria in patients with epithelial ovarian cancer treated with platinum or paclitaxel

Purpose: To assess CA-125 as a measure of response in patients treated with paclitaxel. Patients and Methods: One hundred forty-four patients treated with paclitax el derived from four different trials and 625 patients treated with platinu m from two trials were analyzed using precisely defined 50% and 75% reducti ons in CA-125. The standard and CA-125 response rates to paclitaxel and pla tinum were compared. In addition, we analyzed individual patient groups in which there was a difference in response according to the two response crit eria. Results: Patients with stable disease as determined by standard criteria wh o were treated with platinum and responded according to CA-125 criteria hav e an improved median progression-free survival compared with patients with stable disease who did not respond according to CA-125 criteria (10.6 v 4.8 months; P <.001). Standard and CA-125 response rates for patients treated with platinum (58.93% v 61.31%, respectively) and paclitaxel (30.65% v 31.6 7%, respectively) were very similar, as were rates of false-positive predic tion of response by CA-125 (platinum 2.2% and paclitaxel 2.9%). Responders to paclitaxel had a significantly improved progression-free survival compar ed with nonresponders by both standard criteria (median progression-free su rvival, 6.8 v 2.5 months; P <.001) and CA-125 criteria (median progression- free survival, 6.8 v 3.4 months; P <.001). Conclusion: For assessing activity of therapy for ovarian cancer, these dat a show that precise 50% or 75% CA-125 response criteria are as sensitive as standard response criteria. We propose that they may be used as a measure of response in lieu of or in addition to standard response criteria in clin ical trials involving epithelial ovarian cancer. Sensitivity is maintained whether patients are treated with platinum or paclitaxel. (C) 1999 by Ameri can Society of Clinical Oncology.