The United States Congress defines personalized medicine as "the application of genomic and molecular data to better target the delivery of health care, facilitate the discovery and clinical testing of new products, and help determine a person's predisposition to a particular disease or condition." Traditionally, much of medical practice relies on standards of care based on epidemiologic studies of large cohorts. This approach to evidence-based medicine has revolutionized medicine during the past 50 years. However, results from large population-based studies are not always applicable to a specific individual, and physicians generally take into account specific characteristics—such as age, gender, height, weight, diet, and environment—when evaluating an individual patient.
Recent developments in a number of molecular profiling technologies, including proteomic profiling, metabolomic analysis, and genomic/genetic testing allow the development of personalized medicine and predictive medicine, which is the combination of comprehensive molecular testing with proactive, personalized preventive medicine. It is hoped that personalized medicine will allow health care providers to focus their attention on factors specific to an individual patient to provide individualized care. However, some question whether personalized medicine represents a true departure from traditional medical practice or is an evolutionary transition based on the latest technology.
The overarching concept that underpins personalized medicine is that information about a patient's protein, gene or metabolite profile could be used to tailor medical care to that individual's needs. A key attribute of personalized medicine is the development of so-called companion diagnostics, whereby specific molecular assays that measure levels of proteins or genes or specific mutations are used to stratify disease status, select from among different medications and tailor dosages, provide a specific therapy for an individual's condition, or initiate a preventative measure that is particularly suited to that patient at the time of administration.
The field of oncology currently is feeling the greatest impact of personalized medicine. Several examples of companion diagnostic tests that now are necessary to obtain before cancer-based therapy include measuring for the erbB2 and EGFR proteins for selecting breast, lung and colorectal cancer patients for specific targeted therapies. As the personalized medicine field advances, tissue-derived molecular information will be combined with an individual's personal medical history, family history, and data from imaging, and other laboratory tests.
The field of personalized medicine raises many ethical issues, business opportunities, humanitarian opportunities, and some challenges.