 Assuming a randomization ratio of 1:1, 282 deaths are required in order to achieve a power of 80 of detecting a hazard ratio of 0.72 in favour of one of the two sequences, translating in an increase of median survival time from 10 to 14 months, with a type I error of 5, two-sided, using the Mantel-Cox version of the log-rank test. With a uniform accrual period of 3 years and a follow-up of 18 months, about 350 patients will be needed to reach the target number of events. 