Role of neo-adjuvant hormonal therapy in the treatment of breast cancer: a review of clinical trials

Catherine Abrial,^1,2 Xavier Durando,^1,2 Marie-Ange Mouret-Reynier,^1,2 Emilie Thivat,^1,2 Mathilde Bayet-Robert,^1,2 Béatrice Nayl,¹ Pascale Dubray,¹ Christophe Pomel,¹ Philippe Chollet,^1,2,3 F Penault-Llorca^1,2

¹Centre Jean Perrin, ²EA 4231, Université d’Auvergne, ³Centre d’Investigation Clinique, Clermont-Ferrand, France

Abstract: The clinical benefits of endocrine therapy for patients with hormonosensitive breast cancer are well established. For many years, 5 years of tamoxifen was the gold standard of adjuvant treatment. The recent development of new endocrine agents provides physicians with a more effective therapeutic approach. Nevertheless, the success of neoadjuvant endocrine therapy is much more recent and less reported in the literature. This article reviews the studies published about neoadjuvant endocrine treatment (tamoxifen and aromatase inhibitors). According to the literature, neoadjuvant endocrine therapy seems to be effective. In contrast to neoadjuvant chemotherapy, neoadjuvant endocrine therapy is well tolerated, with very few patients having to discontinue the treatment because of side effects. It does not constitute a standard treatment but could have potential for elderly women with operable, hormonosensitive, well differentiated and slowly progressing (SBR I) tumor or for patients with lobular MSBR 1 carcinoma (low chemosensitivity). The newer generation of aromatase inhibitors (letrozole, anastrozole, exemestane) appears to be more active (in terms of overall response rates and conservative surgery rate) than tamoxifen. Patients with an estrogen receptor Allred score of 6 and over are more likely to respond and gain a clinical benefit. The optimal duration of neoadjuvant therapy has not yet been investigated in detail. These preliminary results should be confirmed by further studies.

Keywords: aromatase inhibitors, breast cancer, endocrine therapy, neoadjuvant, tamoxifen