STE–CP for 
The calculation of the CP requires the prediction of future data. At the time of the interim analysis, STE–CP assumes the estimated empirical trend for long-term survival probability for each individual, that is, the maximum likelihood estimate of the survival probabilities based on the data observed so far. The trial design aims to assess the outcome of each patient at Determination of the maximum likelihood estimate requires at least one patient with available data; if this is not the case, then an assumed value must be plugged in instead. Since power is calculated under the alternative hypothesis, we will use the a priori assumption for long-term survival under the alternative hypothesis, 
