Purpose: To examine early changes in CA125 relative to objective response in patients with recurrent ovarian cancer treated with pegylated liposomal doxorubicin (PLD) or topotecan and to compare the CA125 trends between the two chemotherapeutics.
Patients and methods: Patients with recurrent ovarian cancer, all of whom had measurable or evaluable disease, were randomized to receive 50 mg/m2 PLD every 28 days (n = 239) or 1.5 mg/m2 topotecan for 5 days every 21 days (n = 235) as part of a previously reported multicenter study. CA125 measurements were obtained prior to therapy and with each cycle of administration. Assessable patients underwent radiographic evaluation for response after two cycles of therapy. Objective responses were compared to trends in CA125 values at the end of cycles 1 and 2. CA125 changes were categorized as baseline (+/-10%), +/- 10%-25% variance, and > 25% variance.
Results: Among patients treated with PLD, 50% of complete responders (CR) and 41% of partial responders (PR) had increases in CA125 from baseline to cycle 1. Increases in CA125 were also seen in topotecan-treated patients; however, fewer patients had increases (20% and 8%, respectively). Overall, 15% of responding patients (CR + PR) receiving PLD and 6% receiving topotecan had elevated CA125 after two cycles of therapy. For those patients achieving a partial response, 19% of PLD-treated patients and 8% of topotecan-treated patients had CA125 levels above baseline at cycle 2.
Conclusions: Considerable intrapatient variation in CA125 values is present among responding patients. Early increases in CA125 may not predict ultimate outcome, especially in PLD-treated patients.