The thesis is based on the following publications: 1. Ejlertsen B, Jensen MB, Mouridsen HT. Excess mortality in postmenopausal women who only receive adjuvant endocrine therapy for estrogen receptor positive breast cancer. Acta Oncol 2014;53:174-85. 2. Ejlertsen B, Jensen MB, Elversang J, Rasmussen BB, Andersson M, Andersen J, Nielsen DL, Cold S, Mouridsen HT. One year of adjuvant tamoxifen com...