The primary objective of a phase III trial is to compare disease-free survival among women with high-risk operable breast cancer following surgical resection of all known disease and randomized to receive as adjuvant therapy either CEF or a new therapy. CEF has been established successfully as a standard adjuvant regimen in Canada; the aim here is to determine whether the addition of a taxane (to form the new regimen) can improve survival outcome over CEF alone. The five-year disease-free survival rate for women receiving CEF alone as adjuvant therapy was estimated at about 60%, and it is hypothesized that the newly formed regimen would improve that rate from 60% to 70%. Find the total sample size needed using a two-sided test at the 0.05 level of significance and a statistical power of 80%.