In this study we aimed to determine whether patients with metastatic cancer have higher levels of serum COMP than patients with early breast cancer, correlate the serum levels of COMP in advanced breast cancer patients with the pathophysiological characteristics of tumors, and to evaluate if COMP serum levels could also be used as an independent prognostic marker as described using immunochemical staining in tumor tissue samples (1). Here, COMP is linked to breast cancer.