A Gynecologic Oncology Group Study of serum CA-125 levels in patients with stage III optimally debulked ovarian cancer treated with intraperitoneal compared to intravenous chemotherapy: An analysis of patients enrolled in GOG 172

Abstract

ObjectiveSerum CA-125 values have been advocated in the monitoring of ovarian cancer patients receiving intravenous (IV) chemotherapy. This evaluation sought to determine if the CA-125 test can be used to monitor treatment effect among patients receiving intraperitoneal chemotherapy (IP). MethodsPatient charts from a phase III clinical trial (GOG 172) were retrospectively reviewed. Serum CA-125 levels prior to each cycle of therapy were collected and compared between the IV and IP chemotherapy delivery. The association between CA-125 and progression-free survival (PFS) or overall survival (OS) was estimated and the homogeneity of the results between IP and IV chemotherapy was assessed. ResultsA total of 177 patients were treated with IV chemotherapy and 165 patients with IP chemotherapy with CA-125 data available were included in this analysis. The observed difference was not statistically significant in median CA-125 levels between the IV and IP arms at any time point (P > 0.05 for all). Following surgery and adjuvant chemotherapy, patients with an abnormal CA-125 > 35 U/ml were 2.45 times more likely to have disease progression (95% CI: 1.52–3.95, P < 0.001) and 2.78 times more likely to die of disease (95% CI: 1.66–4.65, P < 0.001), compared to those with a CA-125 < 35 U/ml. These results were consistent with IP and IV chemotherapy. ConclusionSerum CA-125 levels decrease in a similar manner during IP chemotherapy when compared to IV chemotherapy. Serum CA-125 algorithms for monitoring treatment effect that have been established for IV chemotherapy may also be applied for patients receiving IP chemotherapy.