['Previous reports described the prognostic value of the serum CA125 level after primary treatment (CA125 nadir) in a selection of ovarian cancer patients. Our primary objective was to determine whether the CA125 nadir level is of prognostic value on the progression-free survival (PFS) and on overall survival (OS) in epithelial ovarian cancer (EOC) patients in all stages of disease who reached complete remission (CR).', 'Patients were selected from a population-based study on EOC patients diagnosed between 1996 and 2006 in 11 Dutch hospitals. All 331 patients who reached CR (i.e. no physical or radiological signs of residual disease and CA125 values ≤35 kU/L) after primary treatment were included. The Kaplan-Meier survival curves of PFS and OS in CA125 nadir ≤5 kU/L and >5 kU/L were compared using the log-rank test. Multivariate Cox regression analyses were performed to study the factors that independently influence survival.', 'A CA125 nadir ≤5 kU/L (n=69) was significantly associated with both a longer PFS and longer OS (log-rank test P<0.01 and P=0.03, respectively). The CA125 nadir was an independent prognostic variable (HR=1.51, 95% CI: 1.04-2.31) for PFS next to histological type, FIGO stage and residual tumor after surgery.'] Is cA125 nadir concentration an independent predictor of tumor recurrence in patients with ovarian cancer : a population-based study?