[gdpawel]

When breast cancer presents as locally advanced disease, it is customarily treated with neoadjuvant (preoperative) chemotherapy, followed by definitive surgery. At the time of surgery, the specimen is assessed to determine if all visible tumor has been destroyed by chemotherapy. When this happens, it is said to be a “pathological complete response” (pCR). The pharmacogenomic predictors developed from "cell-line" studies (not fresh cells) were evaluated for their ability to predict patient pCR, using the supervised principle component regression method.

Using the CellSearch technique that quantifies circulating tumor cells, German investigators had shown that neoadjuvant chemotherapy with paclitaxel (taxol) caused a massive release of cells into the circulation, while at the same time reduced the size of the tumor. The finding helped explain the fact that complete pathologic responses do not correlate well with improvements in survival.