["State of the art" of adjuvant chemo-endocrine therapy for breast cancer in Japan].

Breast cancer is a solid tumor moderately responsive to chemotherapy and/or endocrine therapy. Based upon meta-analysis covering 233 prospective randomized clinical trials, a consensus about adjuvant chemo and endocrine therapy has been reached according to prognostic factors, including nodal status, tumor size, estrogen receptor and histological grade. The preventive effect of tamoxifen against recurrence has been also proven in Japanese ACETBC (adjuvant chemoendocrine therapy for breast cancer) trials and KEIO BR1 trial. Several other prospective randomized trials have been run in Japan, and the results will be obtained within several years. The features of breast cancer in Japan are low incidence and good prognosis. In these circumstances, the accrual of a vast number of patients and multi-institutional collaboration are essential. The issues under investigation include best chemotherapy dosage and duration, identification of risk factors and the role of preoperative chemotherapy.