Nadir CA-125 has prognostic value for recurrence, but not for survival in patients with ovarian cancer

The objective of this study was to evaluate the nadir CA-125 in patients with epithelial ovarian cancer. A total of 168 patients who achieved complete remission (no clinical and radiological signs, CA-125 ≤ 35 U/ml) after first-line treatment were enrolled in the study. The relationship between CA-125 and survival was examined by applying generalized additive models to the Cox proportional hazards model. The median CA-125 concentration after the treatment was 10 U/ml (2.7–35 U/ml). The nadir CA-125 was related to progression-free survival but not to overall survival. The risk of recurrence in patients with 11–25 U/ml and 26–35 U/ml compared to patients with ≤ 10 U/ml was 1.87 (p < 0.0024) and 2.17 (p < 0.018), respectively. An increased risk of recurrence according to the nadir CA-125 (≤ 10 U/ml vs. 11–25 U/ml and ≤ 10 U/ml vs. 26–35 U/ml) was found in patients with high-grade tumours (hazard ratio, HR = 2.08 and 2.59, respectively), advanced disease (HR = 2.38 and 2.03, respectively), serous histology (HR = 2.08 and 2.43, respectively) and after complete cytoreduction (HR = 2.7 and 2.72, respectively). No correlation between the CA-125 nadir and recurrence risk was found in patients with early-stage disease or those receiving neoadjuvant chemotherapy or bevacizumab.