Precision cancer medicine is a medical practice that optimizes therapy, predicts prognosis, and prevents the onset of diseases through the use of genomic information from cancer tissues. Recent progress in comprehensive genetic analyses using next generation sequencing and various molecular targeted drugs for cancers with specific mutations have enabled us to use precision cancer medicine. When comprehensive genetic analyses are performed on cancer cells, many genetic mutations will be revealed. Among them, driver mutations in known therapeutic targets should be identified. For this purpose, the knowledge of bioinformatics is necessary. Furthermore, bioinformatics provides unintentional, secondary findings in about one in 10 people. Therefore, pre- and post-genetic counselling would be required. In conclusion, the use of precision cancer medicine should involve a team, so that it is implemented with correct understanding of the benefits obtained and the disadvantages that may occur due to comprehensive genome analyses.

Understanding the genomic landscape of malignant tumors has revealed novel diagnostic, prognostic, and predictive molecular biomarkers to refine their pathological classifications. However, it remains a major challenge to incorporate molecular genetic information into the routine diagnostics of cancer to achieve "Precision Medicine." Significant progress towards this goal has been achieved owing to the new World Health Organization (WHO) 2016 Classification of Tumors of the Central Nervous System which has enabled traditional histology-based diagnostics to be replaced with a multi-layered approach that combines histologic features and molecular information in an "integrated diagnosis." Described here are state-of-the-art pathological diagnostic approaches using molecular markers for malignant tumors, focusing particularly on brain tumors, which are likely to help ensure more precise diagnostics for personalized medicine.

In recent years, technological innovations in radiotherapy have been remarkable, thanks to progress in computer technology and therapeutic equipment, and various high precision radiotherapy have been established.

Intensity-modulated radiation therapy (IMRT) can conduct complicated dose calculations by computer control and inverse planning and allows sufficient target dose applications while keeping the risk organs within the tolerance dose. Volumetric-modulated arc therapy (VMAT) is an irradiation technique that adds intensity-modulation to conformal radiotherapy, which shortens the treatment time. Image-guided radiotherapy (IGRT) is an irradiation technique that reproduces the irradiation position, which is determined by the treatment plan, by three-dimensional measurements.

Particle therapy is a form of high-precision radiotherapy that uses protons and heavy-particles (carbon-ion), which are obtained from large accelerators, such as cyclotrons and synchrotrons. Since the particle does not advance beyond a certain depth, called Bragg peak, it is possible to concentrate the dose onto the lesion. Particle therapy has the advantage of providing a low radiation dose to risk organs; thus, the risk of adverse events is low.

High-precision radiotherapy is expected to improve treatment outcomes and reduce side effects.

Since the approval and introduction of imatinib as the first molecular-targeted drug for the treatment of chronic myelogenous leukemia in 2001, more than 50 cancer targeted drugs have been approved in Japan. The molecular targeted drugs have shown prominent efficacy in several cancers caused by the corresponding target molecules. Over recent years, development of biomarkers, companion diagnostics, and next generation sequencing analysis for prediction of clinical outcome facilitated the selection of appropriate drug for patients. The molecular targeted drugs are classified into two groups, monoclonal antibodies and small molecules, which have various mechanisms of action, including inhibition of tyrosine kinases, tumor angiogenesis, and immune checkpoint. Various mechanisms of action of drugs may also exhibit unique adverse events that have not been previously observed. Continuous changes in cancer genomes lead to tumor heterogeneity, which in turn may fuel drug resistance. To overcome these issues, identification of new therapeutic targets and a large number of clinical trials with novel designs are in progress for realization of cancer precision medicine. Here, we summarize recent findings of molecular targeted drugs.