A drug is approved for market use only after a clinical trial has shown that it is safe and that it effectively treats a certain condition. Once the drug is on the market, it can then only be used to treat patients who have that same condition. If an approved drug is used to treat a condition other than the one studied in the trial, this is known as an ‘off-label’ use of the drug.

Using a drug off-label is not a recommended in most cases. However, research has shown that it is particularly common to use off-label drugs when treating cancer patients, and there are several reasons for this.

  • Firstly, cancer is an extremely varied disease. There are over 100 different types of cancer, and a multitude of different causes, ranging from radiation, to chemicals, to viruses. As such, there is no one treatment that works for all cancer patients. Instead there are multiple different approaches to cancer care and lots of different drugs that can be used. Some of these drugs can be effective against more than one type of cancer. However, companies will often not be able to establish separate clinical trials for each cancer type, meaning that the drugs cannot be approved for the multiple indications.
  • Secondly, using combination chemotherapy, i.e. the use of more than one drug to treat a patient, is an effective treatment option for several different types of cancer. However, the FDA does not tend to approve combinations of chemotherapy because there are so many different combinations that it would not be practical to approve each one. This means that the combination of drugs used by a particular patient can often be made up of one or more drugs that are not approved for that patient’s condition.
  • Thirdly, because cancer is such a devastating disease, that affects just under 40% of men and women worldwide, there is a lot of time and money spent on researching suitable treatment options. Many research studies, instead of focusing on developing new treatments, focus on finding new uses for the drugs that have already been approved. The results of these studies are published in medical journals which are then used by the medical community to find additional uses for already approved cancer drugs.

Although the above reasons highlight why using off-label drugs is so common among cancer patients, it can still be risky, and physicians must always base their decision to use these drugs on sound medical evidence.