[Tumor markers in breast cancer]

A number of breast cancer-orientated tumor markers have been utilized for various purposes in clinical practice in Japan. Their purposes are as follows: early detection of primary tumors, prediction of disease extent and prognosis, early detection of recurrent diseases, evaluation of therapeutic responses, monitoring patient outcome, and differential diagnosis of metastatic tumors of unknown origin. The clinical significance of the measurement of tumor markers for these purposes is overviewed in this article. In addition, the results are summarized for two clinical studies conducted by the Tumor Marker Study Group of Japanese Breast Cancer Society (Chairperson: Dr. Kurebayashi), a questionnaire survey on the current status of tumor markers in breast cancer in Japan and a multi-institutional study on the utility of tumor markers for evaluation of therapeutic responses. Future directions of clinical and experimental research for breast cancer-orientated tumor markers are also discussed.