One of the main causes of failure in the treatment of cancer is the development of drug resistance by the cancer cells. The design of cancer chemotherapy has become increasingly sophisticated, yet there is no cancer treatment that is 100% effective against disseminated cancer. Resistance to treatment with anticancer drugs results from a variety of factors including individual variations in patients and somatic cell genetic differences in tumors, even those from the same tissue of origin. Frequently, resistance is intrinsic to the cancer, but as therapy becomes more and more effective,...