CEACAM5 and medullary thyroid gland carcinoma: Since Ct and CEA doubling times (DT) had been shown to be of a prognostic value for survival in MTC (Barbet et al., 2005), patients were stratified accordingly; OS was significantly longer in high-risk (Ct DT < 2 years) treated compared to high-risk untreated patients (median OS, 110 vs. 61 months; P < 0.030).