Letrozole (Femara) is a more effective anti-proliferative agent than tamoxifen irrespective of ErbB1 and/or ErbB2 positive status: evidence from a phase III randomized trial of neoadjuvant endocrine therapy for postmenopausal women with estrogen receptor positive primary breast cancer - Ellis,M.J.; Jaenicke,F.; llombart-Cussac,A. (Breast Cancer Res Treat, 2001)