CA 125 assay in the extension assessment of newly diagnosed breast cancers: why and how?

CA 125 assay is sometimes combined in practice with the one of CA 15-3 and CEA in the extension assessment of breast cancers. `The purpose of this work is to evaluate the contribution of the initial CA 125 as an indicator of distant metastases (DM) or of serous inflammation (SI). This retrospective study concerns a population of 620 patients with breast cancer without metastatic extension (n=325) or metastatic breast cancer (n=295) diagnosed at the Georges-Francois Leclerc center from 1998 to 2014. Seventy-four patients had SI. We showed that initial CA 125 level is linked to the TNM clinic status, the HER2 status, the nature and the number of metastatic locations, the inflammation of the tumor or serous. The ROC curves and logistic regression analyses show that CA 125 is an independent predictive criterion of DM presence (threshold of 55 kU/L): this is the only positive marker in 7% of patients with DM. At the threshold of 110 kU/L, the CA 125 is the only predictive biologic factor for SI. In conclusion, these data present the independent predictive value of CA 125 on the presence of DM or SI on condition of using a specific threshold for each of these uses.