Biological markers in breast cancer prognosis and treatment.

: In this review we will provide a synopsis of the biological markers used in the care of breast cancer patients with emphasis on clinical application. The advent of molecular technology has incorporated new biomarkers along with the older immunohistochemical and serum ones. Serum tumor markers are proteins shed from breast cancer cells. Their levels have long been used as a measure of tumor burden and disease progression or recurrence. However, limitations exist that should be known to those involved in breast cancer management. Historically, immunohistochemical markers have been used to guide treatment decisions. These markers reveal characteristics of the cancer cells and have been used both as prognostic and predictive factors. Molecular markers give information on the expression of certain genes in tumor tissues related to proliferation, invasion, and metastasis and researchers try to correlate them with the use of mathematical modeling with clinical outcomes, hence those markers exhibit prognostic and predictive significance. All these tools can guide personalized treatment by estimating patient prognosis and risk of relapse and tailor accordingly therapeutic approaches.