The delicate balance between the desired and undesired effects of medical treatment is particularly evident in oncology, in which the therapeutic window may be narrow. Radiation and medical oncologists routinely administer therapies that may be toxic to adjacent or distant healthy functional tissues as well as the cancer. Patients and oncologists must accept a certain level of normal tissue toxic effects in exchange for, or along with, therapeutic benefits. The toxic effects associated with chemotherapy and radiotherapy are thus often viewed as a “necessary evil.” Unnecessary toxic effects to healthy tissues, however, is not an acceptable consequence of cancer therapy when effective methods for their elimination or amelioration are available, and those methods should not be withheld from patients.