Why is off-label use of drugs so common in cancer treatment?
A 1991 study by the U.S. General Accounting Office found that one-third of all drug administrations to cancer patients were off label and more than half of cancer patients received at least one drug for an off-label indication. Frequently the standard of care for a particular type or stage of cancer involves the off-label use of one or more drugs.
Off-label use of drugs is widespread in cancer treatment for several reasons.
Some cancer drugs are found to be effective against a variety of tumor types.
The mechanism of action of a drug (the way it works in the body) often suggests that the drug might be effective against tumor types other than those for which it is approved.
For example, Platinol (cisplatin) works to halt the uncontrolled growth of cancer cells by interrupting the copying of DNA in growing cells. Because uncontrolled cell growth is part of most cancers, cisplatin is often used in the treatment of thyroid and lung cancers although it is only approved to treat bladder, testicular and ovarian cancers.
Once a drug is on the market further research may show that it also acts on different biological targets present in other kinds of cancer. Doctors may then begin to use the drug off label to treat those other cancers.
* Cancer chemotherapy often involves the use of multiple drugs.
Multiple-drug treatment regimens have been shown to be effective in several types of cancer, including lymphoma, leukemia, bladder, testicular and breast cancer. The regimens might include one or more drugs not approved specifically for that disease. Also, the FDA generally does not approve multidrug regimens themselves, in part because such regimens are so numerous as to make separate approvals impractical. Multidrug regimens change over time as doctors try different combinations and observe which regimens seem to produce the greatest benefit for patients."