Association between pretreatment CA-125 levels and surgically documented complete responses in patients with ovarian cancer treated with second-line intraperitoneal therapy

Approximately 20%-40% of patients with small-volume residual ovarian cancer, following systemically administered platinum-based chemotherapy, will respond to a second-line intraperitoneal treatment regimen. In an effort to improve the selection criteria for patients being considered for this regional therapeutic approach, we retrospectively evaluated the influence of pretreatment CA-125 levels on the ability of a group of 70 patients with small-volume residual ovarian cancer (no tumor mass>1 cm in diameter) to achieve a surgically defined complete response (S-CR) following treatment on one of three phase-2 intraperitoneal chemotherapy trials conducted at the Memorial Sloan-Kettering Cancer Center. Overall, 18/46 (39%) patients with normal pretreatment CA-125 levels (≦units/ml) achieved a S-CR, compared to only 4/24 patients (17%) with an elevated pretreatment value (χ²= 3.7, P>0.5). Despite the lower S-CR rate in patients with elevated CA-125 levels, the duration of response and survival were similar in the two patient populations achieving a S-CR. Thus, we conclude that an elevated pretreatment CA-125 level in a patient with small-volume residual ovarian cancer should not be used by itself to disqualify an individual from consideration for a second-line intraperitoneal treatment regimen, although the finding suggests a reduced likelihood of achieving a S-CR with this therapeutic approach.