Precision medicine (PM) is a medical model that proposes the customization of healthcare, with medical decisions, treatments, practices, or products being tailored to the individual patient. In this model, diagnostic testing is often employed for selecting appropriate and optimal therapies based on the context of a patient’s genetic content or other molecular or cellular analysis. Tools employed in precision medicine can include molecular diagnostics, imaging, and analytics.
Relationship to personalized medicine
In explaining the distinction from a similar common term of personalized medicine, the National Research Council explains:
Precision Medicine refers to the tailoring of medical treatment to the individual characteristics of each patient. It does not literally mean the creation of drugs or medical devices that are unique to a patient, but rather the ability to classify individuals into subpopulations that differ in their susceptibility to a particular disease, in the biology or prognosis of those diseases they may develop, or in their response to a specific treatment. Preventive or therapeutic interventions can then be concentrated on those who will benefit, sparing expense and side effects for those who will not. Although the term 'personalized medicine' is also used to convey this meaning, that term is sometimes misinterpreted as implying that unique treatments can be designed for each individual.
precision medicine industry was valued at USD 38,878.6 Mn in 2015, and is expected to reach USD 98,250.4 Mn by 2023, expanding at a CAGR of 12.3% from 2016 to 2023
On the other hand, use of the term "precision medicine" as well can extend beyond treatment selection to also cover creating unique medical products for particular individuals—for example, "...patient-specific tissue or organs to tailor treatments for different people." Hence, the term in practice has so much overlap with "personalized medicine" that they are often used interchangeably.
Precision medicine often involves the application of panomic analysis and systems biology to analyze the cause of an individual patient's disease at the molecular level and then to utilize targeted treatments (possibly in combination) to address that individual patient's disease process. The patient's response is then tracked as closely as possible, often using surrogate measures such as tumor load (v. true outcomes, such as 5 year survival rate), and the treatment finely adapted to the patient's response. The branch of precision medicine that addresses cancer is referred to as "precision oncology".
Inter-personal difference of molecular pathology is diverse, so as inter-personal difference in the exposome, which influence disease processes through the interactome within the tissue microenvironment, differentially from person to person. As the theoretical basis of precision medicine, the "unique disease principle" emerged to embrace the ubiquitous phenomenon of heterogeneity of disease etiology and pathogenesis. The unique disease principle was first described in neoplastic diseases as the unique tumor principle. As the exposome is a common concept of epidemiology, precision medicine is intertwined with molecular pathological epidemiology, which is capable of identifying potential biomarkers for precision medicine.
The ability to provide precision medicine to patients in routine clinical settings depends on the availability of molecular profiling tests, e.g. individual germline DNA sequencing. While precision medicine currently individualizes treatment mainly on the basis of genomic tests (e.g. Oncotype DX), several promising technology modalities are being developed, from techniques combining spectrometry and computational power to real-time imaging of drug effects in the body. Many different aspects of precision medicine are tested in research settings (e.g., proteome, microbiome), but in routine practice not all available inputs are used. The ability to practice precision medicine is also dependent on the knowledge bases available to assist clinicians in taking action based on test results.
On the treatment side, PM can involve the use of customized medical products such drug cocktails produced by pharmacy compounding or customized devices. It can also prevent harmful drug interactions, increase overall efficiency when prescribing medications, and reduce costs associated with healthcare.
Artificial intelligence in Precision Medicine
Artificial intelligence is providing paradigm shift toward precision medicine. Machine learning algorithms are used for genomic sequence and to analyze and draw inferences from the vast amounts of data patients and healthcare institutions recorded in every moment . AI techniques are used in precision cardiovascular medicine to understand genotypes and phenotypes in existing diseases, improve the quality of patient care, enable cost-effectiveness, and reduce readmission and mortality rates. 
Precision Medicine Initiative
In his 2015 State of the Union address, U.S. President Barack Obama stated his intention to fund an amount of $215 million  to the "Precision Medicine Initiative" of United States national. A short-term goal of the Precision Medicine Initiative was to expand cancer genomics to develop better prevention and treatment methods. In the long-term, the Precision Medicine Initiative aimed to build a comprehensive scientific knowledge base by creating a national network of scientists and embarking on a national cohort study of one million Americans to expand our understanding of health and disease. The Mission Statement of the Precision Medicine Initiative read: "To enable a new era of medicine through research, technology, and policies that empower patients, researchers, and providers to work together toward development of individualized treatments". In 2016 this initiative was renamed "All of Us" and an initial pilot project had enrolled about 10,000 people by January 2018.
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