Introduction: Rationale for Precision Medicine Clinical Trials.- The Key Role of Pathology in the Context of Precision Medicine Trials -- Basis for Molecular Genetics in Cancer -- Microarrays Based Molecular Profiling to Identify Genomic Alterations -- High Throughput Technologies: DNA and RNA Sequencing Strategies and Potential -- Bioinformatics for Precision Medicine in Oncology -- Assessment of Biomarkers? Predictive Value of Efficacy -- Designs for Evaluating Precision Medicine Trials -- Conclusions and Perspectives: Challenges for the Clinical Implementation of Precision Medicine Trials.