ABSTRACT
The selection of adjuvant chemotherapy for breast cancer is currently more of an art than a science. Several combination chemotherapy regimens can improve disease-free and overall survival of stage I to stage III breast cancer when used as adjuvant (postoperative) or neoadjuvant (preoperative) therapy. Choosing the best possible adjuvant or neoadjuvant chemotherapy regimen for an individual is important because the right choice may make the difference between cure and relapse. Preoperative chemotherapy is the current standard of care for locally advanced breast cancer because this treatment often renders previously inoperable cancers amenable to surgery due to frequent and substantial tumor responses. Gene expression profiling with DNA microarrays represents a relatively recent tissue analysis tool that was developed in the early 1990s. This technology enables investigators to measure, in a semiquantitative manner in a single experiment, the expression of almost all mRNAs expressed in a small piece of cancer tissue.
