Prognostic significance of the CA 125 initial half-life measured during first-line chemotherapy in 62 patients with epithelial ovarian cancer stage III or IV.

The prognostic value of CA 125 initial half-life in serum (Tb) during the first cycles of first-line chemotherapy was studied in 62 patients with stage III or IV ovarian cancer. The half-life was strongly correlated; 1) with the rate of biological remission (P < 0.001). This one was respectively equal to 94.7% when Tb was lower than 20 days, 66.6% when Tb was between 20 and 40 days and 7.7% when Tb was higher than 40 days; 2) with the rate of histological remission (P < 0.001) which was equal to 66.6% when Tb was lower than 13 days; 3) with the speed of recurrence growth measured by the doubling time (dT) of CA 125. The median of dT was equal to 182 days when Tb was lower than 13 days, 63 days when Tb was between 13 and 20 days (P < 0.02) and 38 days when Tb was higher than 20 days (P < 0.001); 4) with the duration of disease-free survival (DFS) (P < 0.0001): the medians were equal to 23.9 months, 18.0 months, 12.0 months, and 5.5 months, respectively, where Tb was lower than 13 days, between 13 and 20 days; 20 and 40 days, and higher than 40 days; and 5) with the duration of overall survival (OS). The probability of survival at five years was equal to 48% when Tb was lower than 13 days. This probability falled to 13%, 12%, and 8%, when Tb was respectively between 13 and 20 days, 20 and 40 days and higher than 40 days. Multiple regression analysis showed that CA 125 half-life was the most important prognostic factor for DFS and OS. Analysis of correlation allowed to identify a relation between: 1) dT and Tb [Td = Tb/[-0,305 + (0,0388)(Tb)]; P < 10(-4)]; 2) the slope of CA 125 initial regression (P) and DFS [DFS = 201, 9e (-16,64*P); P < 10(-8)]; 3) P and OS [OS = 285.0e(-17,00*P); P < 10(-7)]. The initial CA 125 half-life measured during the first cycles of first time chemotherapy seemed to be a critical predictor of response to therapy.