Overview of neoadjuvant endocrine therapy for receptor positive breast cancer in post menopausal women

For elderly women, great importance is increasingly being attached to the question of breast conservation. Current data confirms the concept of neoadjuvant endocrine therapy as an option in postmenopausal women to reduce the volume of locally advanced carcinomas and thereby increase the rate of breast conserving operations. Moreover, in vivo testing of the effectiveness of endocrine neoadjuvance is important for subsequent adjuvant therapy. Endocrine therapy is also particularly well tolerated. Current data are available, although to different degrees, both for tamoxifen and for all aromatase inhibitors. Initial neoadjuvant treatment studies with tamoxifen showed clinical response rates of 49 to 68% with a median reduction in tumour volume of 58%. Studies comparing adjuvant tamoxifen with primary tamoxifen treatment and subsequent surgery in the event of disease progression found no difference in total survival. For the aromatase inhibitors, results were variable overall: In the IMPACT study (Phase III) anastrozole, tamoxifen or the two drugs combined showed no difference with respect to response after 3 months (anastrozole 37.2%, tamoxifen 36.1%); an increased rate of breast conserving operations was achieved with anastrozole (45.2%) compared with tamoxifen (22.2%). Exemestane, at 88.6%, has a greater response than tamoxifen (57.2%) (Phase II) and letrozole shows a response of 55-92% compared with 36% for tamoxifen (Phase II and III). Extension of the neoadjuvant therapy phase with exemestane to 4-5 months improved the response, with further increases in the rates of complete remission based on clinical and pathological evidence and an increased rate of breast conservation of 45.2%; figures for letrozole at 6-8 months were 67.0%. Data on the long-term outcome are not yet available. Future studies are focusing on optimisation of the treatment period, the search for reliable predictive markers and improvement of the therapeutic index.