[Resistance to chemotherapy: current progress]

Chemotherapy has become a very important part of the therapy for several cancers. Complete remission, and sometime cure, can be achieved with this treatment modality. However, when relapse occur, a second remission is seldom obtained. This failure is believed to be linked, at least in part, to the development of drug resistant tumor cells. Our understanding of the mechanisms underlying this resistance, especially regarding the multidrug resistance (MDR) phenomenon, has improved over the recent years. New strategies are being developed to circumvent drug resistance and come now to clinical trials.