Theranostics as a treatment strategy for individual patients encompasses a wide range of subjects, including personalized medicine, pharmacogenomics, and molecular imaging, in order to develop an efficient new targeted therapy and optimize drug selection via a better molecular understanding. Furthermore, theranostics aims to monitor the response to the treatment, to increase drug efficacy and safety, and to eliminate the unnecessary treatment of patients, resulting in significant cost savings for the overall healthcare system. Highly characteristic and nonrandom mutation patterns are found in well-studied oncogenes and tumor suppressor genes. Oncogenes are recurrently mutated at the same amino acid positions, leading to increased activity of the corresponding proteins.