%0 Journal Article
%T Update on endocrine aspects of breast cancer: Report from the 23rd San Antonio Breast Cancer Symposium, San Antonio, Texas, USA, 6-9 December 2000
%A Stephen RD Johnston
%J Breast Cancer Research
%D 2001
%I BioMed Central
%R 10.1186/bcr292
%X The fact that clinical responses are seen with second-line endocrine therapy in ER-positive breast cancer after the development of resistance to tamoxifen implies that some tumours retain partial hormone sensitivity. Several years ago, considerable interest was generated by a small phase II study that suggested substantial activity in tamoxifen-resistant breast cancer with the pure steroidal antioestrogen ICI 182,780, which was devoid of any intrinsic agonist activity. This observation was supported by experimental data in MCF-7 'tamoxifen-resistant' xenografts, which confirmed that ICI 182,780, but not the structurally related triphenylethylene toremiphene, could inhibit the growth of resistant tumours.These observations prompted two large randomized phase III trials to be initiated in women with advanced tamoxifen-resistant breast cancer that compared ICI 182,780 (Faslodex; AstraZeneca, Macclesfield, UK) with anastrozole, and the first data from these trials were reported at the San Antonio meeting. Both trials demonstrated that the clinical efficacy of Faslodex was identical to that of anastrozole in tamoxifen-resistant advanced breast cancer with respect to the primary end-point, namely time to disease progression. In the European trial reported by Howell (Christie Hospital, Manchester, UK) the response rate to Faslodex was 20.7% versus 15.7% for anastrozole, with an additional 23.9 and 29.3% patients, respectively, deriving clinical benefit as determined by stable disease for at least 6 months. In the American study reported by Osborne (Baylor College of Medicine, Houston, TX, USA), which unlike the European study was a double-blind design with a slightly greater number of patients who were known to be ER-positive, the response rates were 17.5% for both arms. Interestingly, there was a nonsignificant trend towards a longer duration of response for Faslodex (median 19.3 versus 10.5 months), and an additional 24.8 and 18.6% of patients, respectively, had stable d
%U http://breast-cancer-research.com/content/3/3/180