Personalized cancer medicine is rapidly becoming a reality in the clinical assessment and management of patients worldwide, and the expectation is that this approach will improve treatment efficacy, reduce toxicity and minimize costs. Offering therapies adapted to the individual patient raises a number of concerns and challenges, of which the most important is the question of intra-tumor heterogeneity. This phenomenon gives rise to heterogeneous clones in the primary tumor which may have diverse potential to progress into metastatic disease, to respond to therapy, and to develop resistance. Our hypothesis is that personally adapted therapy must be based on molecular characterization of the life-threatening metastatic tumor, and target key regulatory molecules in the particular lesion(s). Introduction of person-adapted cancer medicine has been driven by the development of high throughput genomic technologies. Unfortunately, the genomic changes not always mirror the effects of the suggested molecularly targeted drug(s).