Prognostic value of CA125 kinetics and half-life in advanced ovarian cancer

This retrospective study was undertaken in order to assess the prognostic value of prechemotherapy serum CA125 level, CA125 kinetics, and CA125 half-life compared to the ten common clinicopathological variables in patients with advanced ovarian cancer (AOC). CA125 serum levels were determined before and during induction cisplatin polychemotherapy in 222 patients. A prechemotherapy CA125 level higher than 35 U/mL was found in 134 patients. Blood samples were further obtained before each course of chemotherapy (CT). CA125 half-life values were calculated in 112 patients with CA125 levels above 60 U/mL using van der Burg's exponential regression model. The prechemotherapy CA125 level had no prognostic value for survival. However, the median survival time of patients with CA125 levels below the upper normal limit of normality after two courses of CT was 101 months compared to a median survival of 21 months in patients without CA125 normalization (p=0.0000). Half-life calculation showed a significant correlation with survival. The median survival times of patients with T1/2 <20 days and T1/2 >20 days were 101+ and 18 months, respectively (p=0.0003). In a survival analysis using the Cox proportional hazard model, independent prognostic variables for survival included therapeutic response (p<0.0001), Karnofsky index (p<0.0001), residual disease (p<0.0001), tumor grade (p=0.0002), CA125 half-life (p=0.007), and CA125 kinetics (p=0.04). As a consequence, the possibility to predict treatment response by the CA125 half-life during chemotherapy and the time needed for normalization of CA125 levels can divide patients into good and poor prognostic groups early during chemotherapy.