A Open Study of Metronomic Oral Vinorelbine in Combination With Aromatase Inhibitors for the Treatment of Postmenopausal Women With Hormone Receptor Positive,HER2-negative, Advanced Breast Cancer Who Received no Prior Therapy for Advanced Disease

This study is designed to evaluate the clinical effects of the addition of metronomic oral vinorelbine to letrozole and anastrozole. The study will compare the efficacy and tolerability of oral metronomic vinorelbine administered in combination with letrozole or anastrozole, as treatment for hormone receptor-positive advanced or metastatic breast cancer without resistance to Aromatase Inhibitors (AI).