ABSTRACT
I. INTRODUCTION There are several potential advantages and disadvantages of administering systemic therapy before definitive locoregional treatment in early and locally advanced breast cancer. The presence of a measurable mass within the breast permits assessment of response and provides direct in vivo measurements of the sensitivity of the tumor to the particular drug or drugs used. Theoretically the early detection of a resistant tumor should enable both the discontinuation of an ineffective treatment, thereby avoiding unnecessary toxicity, and a change to a potentially more effective therapy. In addition, the earlier the disease is treated the lower the likelihood that resistant tumor clones will emerge spontaneously. Even a short delay in administration of systemic therapy could adversely affect outcome [1]. Another major advantage of early drug treatment is the possibility of making a locally advanced breast cancer operable or making a large operable breast cancer shrink to a sufficient degree to allow breast-conserving surgery rather than mastectomy. The major disadvantage of primary systemic therapy is that the commonly used prognostic factors, in particular axillary node status, are not available before a decision is taken on the use of systemic therapy. However,
it is now possible to determine preoperatively the grade of the cancer and hormone receptor status with the histological diagnosis of the cancer obtained with core biopsy.
