We discuss the role of nutritional science in cancer and summarize the need for this perspective. It is now clear that bio-behavioral factors not only affect cellular immunity but both directly and indirectly modulate fundamental processes in cancer growth, including inflammation, angiogenesis, invasion, and metastasis. It is wrong and simplistic to think that nutrition in cancer patients consists only in some food exclusions. The ultimate goal, therefore, is to restore or enhance the physiological intracellular metabolic pathways, which can be altered in numerous situations. In case of neoplastic disease, the targets are: 1: androgens and insulin-like growth factors (IGF) levels; 2: immunological tolerance; 3: extracellular acid-base balance. The “diet” then should become a real manipulation to promote nutritional therapies, by modulating hormonal parameters, cytokine, as well as acid/base balance.