[Breast cancer--topics from basic research].

The measurement of estrogen and progesterone receptors in human breast cancer provides useful markers for predicting response to endocrine therapy. In human breast cancer, about 90% of unresponsive tumors and 60-80% of tumors responsive to endocrine therapy can be predicted by receptor measurement. Hormone-dependency of breast cancer easily disappears, and endocrine therapy for hormone-dependent cancer markedly encourages disappearance. Since very useful non-steroidal antiestrogens have been synthesized recently, the usefulness of drug-based endocrine therapy for breast cancer has become more important compared with brought about by surgical therapy. To improve the effectiveness of endocrine therapy for hormone-dependent cancer, the proliferation of hormone-independent cancer cells developing from hormone-dependent cancer cells during endocrine therapy should be inhibited. For inhibition, chemotherapy combined with the endocrine therapy and adjuvant endocrine therapy seem to be useful methods for the future.