Circulating tumor markers in breast cancer (review)

The clinical application of circulating tumor markers remains a controversial subject in terms of useful methods and correct interpretation of findings. In particular and despite numerous investigations in the field, we do not have as yet specific or highly sensitive biological markers in breast cancer. Nevertheless, many oncologists often utilize circulating tumor markers in various phases of this malignancy to obtain additional information about disease extent and clinical course. For this reason, we have reviewed the present status of the most widely used serum tumor markers in this neoplasm. Both CEA and TPA are well known, but their organ specificity is not related to breast. Among novel biological markers identified by monoclonal antibodies, special attention has been devoted to circulating agents that are recognized by immunoreagents and that were obtained by immunization with breast-derived products. Both CA 15.3 and MCA are now being validated at the clinical level. From the present review it is clear that today we are still far from being able to make the diagnosis of breast cancer on the sole basis of laboratory findings. On the contrary, some of the available markers can be utilized as prognostic indicators of disease extent and treatment response. Their value greatly increases when combined with conventional diagnostic methods that can be prescribed on the basis of abnormal laboratory findings to confirm or rule out disease recurrence.