Approximately 10-20% of patients diagnosed with non-metastatic breast cancer will require neoadjuvant chemotherapy. In addition, future clinical trials may include 'window-of-opportunity' studies during which biological therapy is administered for a short period (2-3 weeks) while an operable breast cancer patient is awaiting definitive surgery. The majority of early-stage breast cancer patients would be eligible for such trials, allowing the rapid recruitment of breast cancer patients. When coupled with analysis of surrogate markers of response (eg apoptosis, anti-angiogenic effects, etc), these unique clinical trials could provide valuable insights into the biological effects of new therapeutic agents in evaluation.