p53-autoantibody may be more sensitive than CA-125 in monitoring microscopic and macroscopic residual disease after primary therapy for epithelial ovarian cancer.

PURPOSE: To evaluate the use of p53-autoantibodies (p53-aab) for monitoring minimal disease after standard therapy of advanced epithelial ovarian cancer (EOC).
METHODS: Retrospective analysis of p53-aab in preoperative and long-term follow-up serum samples from 10 patients selected for representing three relevant EOC subgroups: platinum-sensitive disease after macroscopic complete debulking (n = 4) and platinum-sensitive (n = 3) or platinum-resistant disease (n = 3), both after suboptimal debulking with residual tumor of <1 cm diameter. p53-aab levels were quantified by a sandwich ELISA in two independent experiments. CA-125 values of all samples and clinical information were retrieved from medical records.
RESULTS: Patients with early relapse (median PFS 7 months, n = 8) had high p53-aab levels throughout follow-up while CA-125 values had dropped below the cut-off after primary surgery during or after chemotherapy in these cases. Patients with seroconversion to p53-aab negativity experienced prolonged PFS (n = 2; #1: 50 months, #2: no evidence of disease for 36 months until last follow-up). Continued p53-aab positivity was not related to the resection status or platinum sensitivity.
CONCLUSIONS: p53-autoantibodies may be a highly sensitive marker for minimal residual tumor mass after surgery and/or chemotherapy rather than standard CA-125, possibly due to the different nature of these markers. CA-125 released by cancer cells is related to tumor mass, whereas p53-aab levels can indicate the presence of few tumor cells due to amplification by the immune system. Seroconversion of p53-aab could be associated with long-term survival.