Urinary N-Telopeptide Is a Rapid Predictor of Response to and Palliative Benefit from Bisphosphonate Therapy in Patients with Metastatic Breast Cancer

Bone is the most common site of metastases in patients with advanced breast cancer. In these patients, the primary aim of therapy is to prevent and delay the occurrence of skeletal-related events (SREs), which can be defined as follows: (1) pain requiring radiation or surgical intervention, (2) spinal cord compression, (3) pathologic fracture, or (4) hypercalcemia. Unfortunately, determining which patients are at highest risk for an SRE is difficult with current imaging techniques. In contrast, the urinary biomarker of bone resorption, collagen N-telopeptide, is under intensive study after repeat validation as a rapid and reliable predictor of SREs as well as prognosis and survival. Herein, we review this new role of collagen N-telopeptide as a predictor of bone involvement and response to treatment, and of the palliative benefit of bisphosphonate therapy in patients with metastatic breast cancer.