For example, more than 60% of cancer patients are over the age of 65 and have anywhere from two to five other chronic illnesses, such as congestive heart failure or high blood pressure. Trials with younger patients would not involve the same mix of health problems.
"You get a younger adult, in the age range of 50..., that doesn't have any diseases other than cancer," said Robert Hauser, senior director of the American Society of Clinical Oncology's (ASCO) Quality Department. "So, once a drug is developed from a trial, it ends up being used on a population that wasn't evaluated on a large scale. Right now, we only learn from 3% of all adult oncology patients because only 3% of them participate in clinical trials for drug development."
And, once a clinical trial ends, patients are no longer tracked, Hauser added.
Also hindering advances in personalized medicine is the compartmentalization of healthcare data at hospitals, private practices and even clinical trials.
Additionally, EHRs use proprietary software, meaning they don't communicate with other systems. An EHR from Meditech, for example, doesn't natively share data with one from Cerner, McKesson or Epic Systems - the four largest EHR makers in the world.
"We realize the data standards wars and interoperability issues that go on amongst EHR vendors is not something that's going to be overcome in the near future," said Josh Mann, assistant director of Oncology Technology Solutions for the ASCO.
There is, however, an industry-wide effort under way to break the logjam.
For example, the non-profit Health Level Seven International this month released standards and guidelines that enable hospitals to exchange medical information, including radiological images.
Beginning in March 2010, $564 million in federal funds were allocated to states to develop health information exchanges, which allow for the sharing of health information electronically through data translation engines that allow EHRs to share information over secure Internet links.
The federal government has developed the Nationwide Health Information Network (NwHIN), which encompasses a set of standards, web services and policies that enable the secure exchange of health information over the Internet.
Currently, health information exchanges are being adopted at the regional, or at best, state-wide levels. Some of the most significant health information sharing networks are being deployed among healthcare providers themselves or by healthcare non-profits.
For example, the ASCO recently completed building a data analytics engine that pulls together information from more than 100,000 breast cancer patients from 27 oncology practices using disparate EHR systems. While still a prototype, the system does represent one of the largest breast cancer data sets in the U.S., according to Hauser.