Zoledronic acid (ZOL), one of the most potent bisphosphonates, has been shown to improve DFS in postmenopausal patients with breast cancer when administered immediately after or following a delay after letrozole administration (ZO-FAST phase III study involving 1065 metastasis-free patients at stages I–III with ER+/PR+breast cancer) [99]. Here, PGR is linked to breast cancer.