Abstract : The «one size fits all» approach is seriously challenged by rapid progression of medical knowledge, especially in the field of individual genome expression. It is currently known that the anti-tumour effect of a given treatment and possible side effects at the level of healthy tissues, can at least partly be predicted and explained by individual variations of gene expression. However, most of us realize that these differences in response are also linked to a variety of other individual characteristics, such as for example the environment and socio-economic factors. Without any possible doubt, there are multiple problems (technical, administrative, financial, cultural and ethical) to be solved, before we witness the real irruption of precision medicine and its holistic individualized approach in our daily oncological practice. It has to start with an international effort, disregarding borders of individual countries, in order to obtain very large amounts of data (with a high degree of variability to avoid bias). This holistic approach, at both societal and individual levels, is the entrance door for a personalized approach in care, whether this is curative, predictive or preventive.