Ovarian cancer is the fourth most common cause of cancer deaths in women. Approximately 75% of patients present with an advanced stage, and because of this, only a minority of patients will have surgically curable localized disease, and systematic chemotherapy has become the primary treatment modality. A randomized phase III trial is considered to compare paclitaxel-carboplatin versus docetaxel- carboplatin as first-line chemotherapy in stage IV epithelial ovarian cancer. Suppose that we plan to use a statistical test at the two-sided 5% level of significance and the study is designed to have 80% power to detect the alternative hypothesis that the two-year survival rates in the paclitaxel and docetaxel arms are 40% and 50%, respectively. Find the total sample size required.