Preoperative therapy in invasive breast cancer: pathologic assessment and systemic therapy issues in operable disease.

PURPOSE: To review the state of the science with respect to preoperative systemic therapy and pathologic assessment in operable breast cancer.
METHODS: This article reviews data presented at the National Cancer Institute State of the Science Conference on Preoperative Therapy in Invasive Breast Cancer as well as supporting published data.
RESULTS: Preoperative chemotherapy in operable breast cancer has been shown to improve breast conservation rates as a result of tumor response to therapy. When patients are given preoperative systemic therapy, regimens should be the same as those established as safe and active in the adjuvant setting. At present, there are no data to suggest that systemic treatment should be tailored based on initial tumor response, or based on the extent of residual disease. In operable breast cancer, there seems to be no survival advantage from initiation of systemic therapy before surgery. A variety of clinical, imaging, and pathologic measurements are available to gauge tumor response to treatment. There is a clear correlation between tumor response in the breast and lymph nodes and both disease-free and overall survival. Pathologic complete response and other pathologic measures may be useful as surrogate end points in evaluating and understanding new therapies.
CONCLUSION: In operable breast cancer, preoperative systemic therapy is effective and can improve breast conservation rates. Unless the tumor is large or the patient is in a clinical trial, postoperative adjuvant systemic therapy is the standard of care. To achieve optimal outcomes, preoperative systemic therapy must be administered as part of a coordinated, multimodality treatment program. The preoperative setting provides a unique opportunity to study the impact of systemic therapies on breast cancer biology.