A pilot study of neoadjuvant paclitaxel and radiation with correlative molecular studies in stage II/III breast cancer.

A commonly used approach to the management of locally advanced breast cancer currently involves neoadjuvant chemotherapy, followed by surgery and radiation. Earlier neoadjuvant regimens had utilized doxorubicin, making concurrent treatment with radiation less desirable given dose-limiting normal tissue toxicities. With the development of paclitaxel, we can now reconsider the use of concurrent chemoradiation in the treatment of breast cancer. Although paclitaxel is a known radiation sensitizer, its precise mechanism of action is still unclear. One of its proposed mechanisms is that it binds tubulin and induces an M-phase arrest. As cells in M-phase are very sensitive to radiation, it thereby increases radiation sensitivity. The ability to predict tumor response for individual patients would allow us to tailor subsequent therapy for the individual patient. This study is designed to evaluate if paclitaxel's effects on the cell cycle of an individual patient can predict the responsiveness of that patient's tumor to paclitaxel and radiation. Patients will be treated with 3 cycles of paclitaxel followed by concurrent paclitaxel and radiation prior to definitive surgery.