[Biomarkers in breast cancer]

Biomarkers are measured in the management of breast cancer patients for the following purposes. (1) Early detection of breast cancer: blood tumor markers such as CA 15-3 are useless for this detection because of a low sensitivity. Proteomics profiling has recently been investigated using blood or nipple aspirate fluid for the detection. Measurement of CEA and HER 2 in abnormal nipple discharge has been approved for diagnosis of breast cancer in Japan. (2) Monitoring of breast cancer patients: serum tumor markers are routinely measured for early detection of recurrent diseases, evaluation of therapeutic response and monitoring outcome of patients by a majority of breast cancer experts in Japan. Study results investigated by the Study Group of the Japanese Breast Cancer Society in 2001 are presented with regard to the questionnaire survey on the present status of tumor marker measurement and the clinical study on usefulness of tumor markers for the evaluation for therapeutic response. (3) Prognostic factors: new biomarkers have been investigated to select patients at high risk for distant metastases, which could not be selected by classic prognostic factors. Three prognostic factors (UPA/PAI-1, cyclin E, gene profiling), which were discussed at the 8th St. Gallen International Consensus Meeting last year, are mainly discussed. (4) Predictive factors for therapeutic response: hormone receptors (HR) have been used as reliable predictive factors for response to endocrine therapy. Other biomarkers have been investigated to select patients with tumors HR-positive but unresponsive to endocrine therapy. Current status, clinical significance, problems and future directions on predictive factors for response to cytotoxic chemotherapy are also discussed.