LDTs, or lab developed tests, are performed not in a hospital lab or physician office. They are sent out to central labs so they generally fall out of FDA's rules. In the past, LDTs were used within a hospital system, one lab, a few physicians. But as certain labs become known for tests, they are seeing broader usage and the companies that perform tests are seeing a healthy business.
Commissioner Hamburg cited the example of OvaSure, which was marketed as a test to detect ovarian cancer but was withdrawn from the market four months after it was launched because oncologists and the FDA found it was not effective.
Kalorama's report on this topic, The World Market for Cancer Diagnostics,