Though our current definition of personalized medicine has evolved with our understanding of the human genome, or the set of genetic information in our cells and bodies, the principles behind the term have been around for centuries.
More than 2,000 years ago, Hippocrates, known as the father of Western medicine, shared the notion that people have different ailments, symptoms and responses to treatments — the idea that a one-size-fits-all approach isn't always the best way to care for each patient [source: Sykiotis et al.].
Later, medical pioneers such as Reuben Ottenberg and Ludvig Hektoen developed a more personalized approach after working on blood transfusions. In 1907, Ottenberg and Hektoen built upon knowledge that people had different blood types. They determined that matching them increased the chances for successful transfusions and lowered the risk of the body rejecting transfused blood [sources: FDA and ARC].
In the 20th century, doctors and researchers continued to personalize medicine by documenting and probing people's family health histories for diseases that were likely to have a genetic component, or to be passed on from generation to generation.
But it wasn't until the advent of the Human Genome Project that personalized medicine took on its current meaning, with a larger focus on the links between genetics and health. This international effort opened the door to mapping series of genes switched "on" or "off" during cancer or disease. Over time, scientists began to build side-by-side comparisons to generalize which sets of genes are involved in diseases among people of diverse ages, backgrounds and heritages through genome-wide association studies.
In 1998, the U.S. Food and Drug Administration — the regulating entity for approving and overseeing drugs, devices and medical treatments — used a personalized medicine approach to approve Herceptin, a drug that targets breast cancer in people whose tumors produce a specific protein [source: FDA]. Because researchers successfully identified what made the drug useful for a subset of people, the treatment gained approval and a place in standard medical practice.
Though population-level studies provide a comparison for personalized medicine, they're only one piece of the puzzle. In order for these studies to take a personalized medicine approach, each person's individual biology also should be explored.
Let's examine this notion and how personalized medicine differs from traditional medicine.