The enormous impact of both clinical and basic research on the field of breast cancer can now be readily appreciated. It is the purpose of this new series of books to bring together the recent major advances in our understanding of the disease. The first volume is devoted exclusively to treatment. It is written by scholars who are actually investigating the biological principles which underlie our current approaches to therapy. For example, countless articles have appeared proposing some ad­ vantage for one surgical approach to primary breast cancer compared with another. The new message is that these arguments for the superior­ ity of one surgical approach over a.nother are valid only in that minority of patients whose disease is absolutely confined to the primary tumor site. It is far less important which surgical approach is selected for the larger group of patients who present with occult distant metastases. The whole subject of adjuvant therapy is still in its infancy. We have progressed from single-agent adjuvant chemotherapy to combined modality regimens consisting of combination chemotherapy plus im­ munotherapy, plus radiotherapy, plus endocrine therapy. It will un­ doubtedly take many years to sort out the proper use of these agents.