While it may be decades before we see the full benefits of personalized medicine, initial benefits are already here. For example, genetic analysis of patients dealing with blood clots, colorectal cancer, and breast cancer are driving treatment advantages that, until recently, were impossible:

Blood clots. Before the availability of genome-based molecular screening, the dosing of Warfarin, which is prescribed 21 million times a year, was a dangerous game in which too little of the drug could trigger more clots and too much could lead to excessive bleeding.

Since 2007, the U.S. Food and Drug Administration has recommended genotyping for all patients being assessed for therapy involving Warfarin. Genotyping allows prescription of drug therapy regimens only to individuals expected to benefit from that specific drug at that specific dosage.

Colorectal cancer. Metastatic colorectal cancer kills 50,000 Americans every year, more lives than are lost to breast cancer and AIDS combined. Among the drugs most frequently used in treating colon cancer is cetuximab (sold as Erbitux by Bristol-Myers Squibb).

For colon cancer patients, the biomarker that predicts how a tumor will respond to certain drugs is a protein encoded by the KRAS gene, which can be now be determined through a simple test. Because cetuximab is effective only in colon cancer patients with normal KRAS protein, treatment with the drug can be withheld from the 40 percent of patients for whom it would prove ineffective. Alternative therapies can be pursued immediately instead.

Breast Cancer. Just as molecular diagnostic testing of tumors determines which colon cancer patients are most likely to benefit from drug therapy using cetuximab, women with breast tumors can be screened to determine which receptors, if any, their tumor cells contain.

For example, the cells of the highly aggressive "triple-negative" breast cancer have no estrogen, progesterone, or human epidermal growth factor receptors, which are essential to the efficacy of current anti-breast cancer therapies. The application of personalized medicine eliminates both the considerable expense and precious time of trial-and-error treatments and helps clinicians to determine quickly which breast cancer therapies are most likely to succeed.

How is personalized medicine affecting our society? Learn more