Cancer cells are originated by normal cells and with those share the need to be fed. Metabolic reprogramming in cancer cells is not yet fully understood, and there is a vast literature suggesting that any macronutrient may be efficiently utilized by cancer for duplication purposes. Metabolic hyperactivity of cancer and continuous duplication requires huge amounts of both energy and substrates for syntheses of components of new cells, and the modifications of metabolism induced by cancer cells to survive and grow damaging lethally, the whole organism. In rodents, we have recently observed that by modifying diet in a way not existent in nature, changing radically the ratios among essential and non-essential amino acids (AA) (usually less than 0.9), largely increasing essential-AA (EAA) percentages, lifespans increased. In vitro, EAA supplementation promoted colon cancer cells (CT116) apoptosis by enhanced autophagy. Therefore, we tested in mice if injection of colon cancer cells would have been followed by unvaried development of cancer volumes in animals fed with standard laboratory diet (controls) versus EAA rich modified diets (EAAmd). Both diets perfectly matched the same total macronutrients and micronutrients contents; only quality of nitrogen was radically different. Results of the first set of 8 animals, 4 controls and 4 EAAmd-fed, showed that controls develop cancers near 5 times larger and heavier than EAAmd-fed (P<0,002) on the same time. We discuss which epigenetic modifications would be involved and worth to be studied, and what kind of scenarios those preliminary findings, if confirmed, would open.