Predictive value of serum CA125 following optimal cytoreductive surgery during weekly cisplatin induction therapy for advanced ovarian cancer

Abstract

One hundred seventy-one patients with epithelial ovarian cancer were treated on a prospective protocol of weekly cisplatin induction (1 mg/kg weekly for four courses) followed by monthly cisplatin (50 mg/m2), Adriamycin (50 mg/m2), and cyclophosphamide (750 mg/m2). Seventy-five patients with FIGO stage III or IV disease who underwent optimal cytoreductive surgery (<2 cm residual disease) were treated on this protocol and had weekly as well as monthly serum CA125 levels measured. A retrospective analysis was performed in order to determine if a > or = 50% fall in elevated serum CA125 levels during weekly cisplatin induction therapy would be predictive of findings at second look operation, normalization of serum CA125 levels (< 35 u/ml) immediately prior to the third course of multiagent chemotherapy, and to determine the impact of such a decline on median progression-free interval. Positive predictive values for this parameter with respect to findings at second look operation ranged between 38% and 50% (P > 0.05). Positive predictive values for this parameter with respect to normalization of serum CA125 levels immediately prior to the third course of multiagent chemotherapy ranged between 64.2% and 89.6% (P > 0.05). Logistic regression analysis demonstrated that a > or = 50% fall observed in CA125 levels during four weekly courses of chemotherapy served as an independent predictor of normalization of serum CA125 levels (<35 u/ml) following two courses of multiagent chemotherapy (P = 0.009) and improved median progression-free interval (P = 0.04). Eighteen patients demonstrated a rise in serum CA125 levels during weekly induction cisplatin chemotherapy. Only one of these patients (5.5%) demonstrated a surgical complete response at the end of standard therapy.