So far, personalized medicine isn't perfectly personalized. New data shows that diagnostic tests to determine whether women should take certain breast cancer drugs have a failure rate of up to one-quarter. So women who should be using Genentech's Herceptin, GlaxoSmithKline's Tykerb, and anti-hormone meds like AstraZeneca's Arimidex and Faslodex, aren't given the chance. Likewise, women with the sort of tumors that don't respond to those drugs are taking them, thinking that they're bound to work.
The problem is that those tests aren't clear-cut, yes-or-no diagnostics like pregnancy tests. They rely on individual pathologists' subjective judgment. And patients are more likely to get a false negative than a false positive, so more patients aren't getting the drugs they need than vice versa. Said one pathologist, "If we tried to market pregnancy tests with this rate of inaccuracy, they would be taken off the market."
- read the report in the Wall Street Journal