Chemotherapy, hormone therapy, and new targeted therapies for cancer lead to adverse effects which are often difficult to relieve using classical homeopathy. Besides diminishing the quality of life of the patient, they can force the oncologist to reduce or even to cease treatment prematurely, which represents a loss of opportunity for the patient. Faced with these recurring problems, would the use of homeopathic dilution of chemotherapy, also called hetero-isotherapy, be a suitable response for improving the tolerance of and the adherence to cancer treatment?