Letrozole in Postmenopausal Hormone-Responsive Early-Stage Breast Cancer

Excerpt

In recent months several groups have reported marked improvement in relapse-free survival when targeted therapy was added to chemotherapy in patients with human epidermal growth factor receptor 2 [HER-2]-positive, early-stage breast cancer. In spite of the significance of these findings, a discovery of even greater importance was the identification of the estrogen receptor (ER) and its relevance in breast cancer. Indeed, the application of hormonal therapy, and tamoxifen in particular, for patients with ER-positive tumours was one of the most important breakthroughs in oncology in the past 50 years. Although equally effective as all other endocrine strategies, tamoxifen has been long established as the endocrine therapy of choice in post-menopausal women with advanced or early hormone-dependent breast cancer. While the tolerability profile of tamoxifen was the primary basis for this distinction, it has, paradoxically, also stimulated a resurgence of interest aimed at antagonising estrogenic activity with less toxicity. A primary target is the enzyme aromatase, which catalyses the conversion of androgens to estrogens. Strategically positioned in the estrogen biosynthetic pathway, inhibition of aromatase can be selective and relatively specific. …