5585 Objective: CA125 is the tumor marker used to evaluate response to chemotherapy in patients with epithelial ovarian cancer (EOC). The aim of this study was to determine if the timing of normalization or percent decrease in CA125 levels during primary chemotherapy could predict survival. Methods: Patients treated at our institution for EOC with primary taxane/platinum-based chemotherapy for 6 cycles between 1996 and 2005 were eligible. Patient demographics, chemotherapy administration, CA125 levels, and survival outcomes were abstracted. Progression-free- survival (PFS), overall survival (OS), and platinum sensitivity (> 6 months from chemotherapy completion) were compared to CA125 levels during primary therapy. Baseline levels, change over time, and timing of CA125 normalization were calculated. Analyses were performed using Kaplan-Meier method and compared using the log-rank test, Chi-square test and Fischer’s exact test. Results: 269 patients with EOC were identified. When stratified by which cycle of chemotherapy achieved normalization, PFS ranged from 25 months at 1st cycle to 4 months at 6th cycle (p< 0.001). OS showed a similar benefit from 74 months at 1st cycle to 22 months at 6th cycle (p<0.001). Platinum sensitivity improved from 23% (normal CA125 after 6th cycle) to 72% (normal CA125 after 1st cycle) (p=0.003). Patients with normalization after the 3rd cycle or sooner compared to patients with normalization after the 4th cycle demonstrated improved PFS (19 vs. 6 months; p<0.001), OS (48 vs. 27 months; p=0.001) and platinum sensitivity (78 vs. 22%; p<0.001). Linear regression models of the slope of the decline of CA125 levels correlated with PFS (p=0.03); however, the models failed to predict an OS advantage. Conclusion: Earlier normalization of CA125 levels during primary chemotherapy for EOC predicts improvement in platinum sensitivity, PFS, and OS. This data provides prognostic information that may influence future decisions regarding chemotherapy. No significant financial relationships to disclose.
