Neoadjuvant chemotherapy for breast cancer determined by chemosensitivity assay achieves better tumor response

Neoadjuvant chemotherapy can potentially reduce tumor size and help downstage the tumor before definitive operation was performed. However, it was not possible to tell whether the patient would respond to the regimen until given. This difficulty can be overcome by testing the susceptibility of a sample of cancer cells in vitro: a "patient-tailored approach". In this pilot study, we attempt to demonstrate an improved response by this "patient-tailored" approach over standard regimen.

The study included 36 women with moderately advanced local breast cancer larger than 2 cm in diameter. Twelve were allocated to receive a standard regimen of 5-fluorouracil, epirubicin and cyclophosphamide (FEC) preoperatively as controls, and 24 were given the most suitable regimen according to testing; the options were FEC, cyclophosphamide, methotrexate and 5-fluorouracil (CMF), 5-fluorouracil, adriamycin and mitomycin C (FAM) and paclitaxel alone. The cell activities of drug-treated solid tumors were compared to controls with a highly sensitive ATP bioluminescence assay. Patients received chemotherapy according to sensitivity results and the tumor area clinically measured before and after chemotherapy.

Sensitivity-directed treatment helped patients achieve a higher rate of complete clinical response (10/24 vs. 0/12), larger mean reduction in tumor area (75% vs. 26%), and 25% pathological complete response (pCR). The paclitaxel subgroup achieved 80% (pCR).

It is a useful in vitro assay to provide a reference of the particular patient who received treatment according to her sensitivity result. It may improve pathologic complete response, clinical tumor response and lead to less extensive surgery.