The FDA has allowed drugs for cancer and other serious diseases to stay on the market even when their effectiveness is unproven. Under the "accelerated approval" program a drug can be made available when preliminary research is promising under the promise of follow-up data. However even after a decade of no additional information the FDA doesn't take any action, in fact it has never pulled a drug approved in this manner from the market. When questioned by the GAO about the issue the FDA said it doesn't even have any plans to get more aggressive on enforcement.
Is this how the FDA protects the public or the drug manufacturers?