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Personalized medicine: Evolution, not revolution

Personalized, or precision, medicine promises a new paradigm of medical treatment, focused on individualized methods of disease diagnostics and treatment. Despite ongoing confusion about the meaning and interchangeability of both terms, personalized medicine broadly refers to “the tailoring of medical treatment to the individual characteristics of each patient,”1 while precision medicine broadly refers to the use of “omics” technology – emerging and ever-more complex genomic and proteomic tools – to identify markers that will subdivide patients into subgroups of expected response rates and facilitate individually targeted treatments.2 Implicit in these new terms is the idea of moving away from prior forms of medical practice: The terms alone insinuate that previously practiced medicine was impersonal and imprecise.

Prioritization of the individual experience is a seemingly natural response to a previous mode of thinking, which by necessity held that all patients in a trial must be similar (according to strictly defined inclusion and exclusion criteria) and treated interchangeably. In that sense, personalized medicine seems a reaction to the idealization of impersonal randomized clinical trials.3 We have, of course, gained extensive medical knowledge through randomized clinical trials despite their limitations. This is offset, however, by the limitation that information learned in these trials often fails to distinguish causes of differential responses between individuals: Even with the gold standard of treatment, some people respond, and some don’t. The existence of the statistical tool “Number Needed to Treat” (NNT) is a clear indication that not all treatments work equally well for patients.4,5

The fact is, however, that physicians have always practiced some form of “personalized” medicine. Humoral treatment was tailored by physicians over the centuries to every individual’s diet and environment. In recent years, aware not only of the NNT statistic, but also of the numerous aspects of study design, outcome variability and potential bias, we all have been faced with the challenge of sorting through the literature to find the best treatments for our individual patients. I review Mrs. A’s, Mr. B’s and Miss C’s comorbidities, current medications, prior adverse reactions and current symptoms before every clinic visit in order to provide each of them with personalized and precise therapeutic recommendations. The careful selection of treatment (agent, dose and course, as well as alternatives) is something I pride myself on, and likely what most of us would pride ourselves on when we are evaluating and treating patients. The acknowledgement of each patient’s personal situation through careful exchange of information is the whole reason to have dedicated patient-physician interaction time, and I would argue that healthcare providers are doing their very best to follow through. Personalized medicine is the medicine we are currently practicing.

So what, precisely, does the advent of personalized or precision medicine mean for us? It can’t simply be about providing more information. Our current practices are increasingly overwhelmed by an onslaught of complex data. We often face an insurmountable mountain of facts and figures impossible for even the most thorough and thoughtful provider to sort through. Complex genetic tests can now be ordered at the click of a button, but unless a provider has the resources (of both time and knowledge) to assess the results, understand their implication, alter the current therapy and effectively communicate that to the patient, the extensive efforts that went into test development and deployment are completely wasted.

There have been amazing successes in the realm of precision treatments that have proven to be life-prolonging for the small number of individuals who are perfect candidates: Gleevec, Tarceva, Herceptin, Ivacaftor, among others. But in many cases, “omic” knowledge is incredibly difficult to harness: Genetic screening companies may reveal possibilities that university researchers and commercial pharmaceutical companies have not been able to exploit in drug development; the necessity of aggregating data across populations may impinge on patient rights in an era of privacy concerns and abuses; the statistical complexities of n-of-1 trials hamper easy generalizations for subsequent patients; the allocation of resources is always contested.

The power of personalized medicine will come only with the infrastructure to allow each individual physician to offer excellent patient-centered diagnostics and therapeutics.6 To be useful, precision medicine must offer individual physicians more than just mounds of data or pages of information. It must offer therapeutic knowledge. As we navigate the inevitable challenges ahead, we must stay focused as a profession on the goal to deliver a personalized experience – a specific diagnosis, with a subsequent therapy that fixes the exact problem, delivered at the right time with the right dose. This vision isn’t a departure from medical tradition but another step in the evolution of our care, and in the improvement of our ability to serve our patients.

Eventually, we may even hope to deliver on the ability to detect the entity in the first place that has the potential to cause disease, and intervene before the disease state occurs. Perhaps by relabeling our current paradigm we can remember to focus on treating patients, not simply disease. But neither relabeling, nor simply adding more data to our files, will necessarily result in the better care that proponents of precision and personalized medicine promise. I, for one, look forward to any development that improves my ability to provide personalized care for my patients, however it is framed or sold.


  1. President’s Council of Advisors on Science and Technology. Priorities for personalized medicine. 2008. Sep, Accessed August 2, 2019.

  2. Collins FS, Varmus H. A New Initiative on Precision Medicine. N Engl J Med. 2015 Feb; 372(9):793-795.

  3. Bittencourt MS. From Evidence-Based Medicine to Precision Health: Using Data to Personalize Care. Arq Bras Cardiol. 2018 Dec; 111(6): 762-763.

  4. Schork NJ. Time for one-person trials. Nature. 2015 Apr; 520: 609-611.

  5. Abrahams E, Silver M. The Case for Personalized Medicine. J Diabetes Sci Technol. 2009 Jul; 3(4): 680-684.

  6. Hamburg MA, Collins FS. The Path to Personalized Medicine. N Engl J Med. 2010 July; 363: 301-304.

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