Some one-third of the chemotherapy drugs used to treat cancer were never approved by federal regulators to fight the cancers they are used for, according to an emerging study.
Chemotherapy drugs, approved by the U.S. Food and Drug Administration (FDA) to fight specific cancers, are often prescribed off-label to treat other tumors for which the drugs are not approved, explained Reuters Health, As we’ve explained, physicians are free to prescribe drugs in a so-called “off-label” way, meaning that an approved medication may be prescribed for a non-approved purpose.
Chemotherapies are types of drugs used to destroy or slow down the growth of cancer cells, which rapidly increase and divide, explained WebMD. The drugs are also known to damage healthy and rapidly dividing cells such as those lining the mouth or intestines or that cause hair to grow. Chemotherapies are known to cause significant side effects.
Chemotherapy can, depending on the cancer type and its stage, cure or control cancer or ease it symptoms and can be used alone or in collaboration with surgery, radiation therapy, or biological therapy, WebMD noted. The type of chemotherapy used depends on the type of cancer involved; some drugs are used in the treatment of a broad array of cancers. While others are used for one or two specific cancers.
Researchers questioned of physicians have been prescribing chemotherapies—very costly and toxic drugs—for unapproved uses, said the study team, which was led by Rena Conti, an assistant professor of health policy and economics at the University of Chicago, said Reuters Health. “The main criticism of off-label prescribing has been the concern that it jeopardizes patient safety because the full risk-benefit ratio is often not completely understood,” wrote University of Toronto’s Dr. Monika Krzyzanowska, according to Reuters Health. Krzyzanowska published an editorial accompanying the study that appeared in the Journal of Clinical Oncology yesterday.
Despite this, said Conti, billions of dollars are spent on off-label chemotherapies and are wasted. “We don’t know what the outcomes are. We can’t make a judgment of whether the off-label use we document … is appropriate or inappropriate,” Conti said, wrote Reuters Health.
For the study, the team used a national prescription database from United States oncologists to estimate how the most commonly used intravenous or injected chemotherapies were used in 2010. The researchers discovered that 10 chemotherapies were patent-protected from competition and ranged from nearly 500,000 doses of Genentech’s Avastin (bevacizumab), which is approved to treat brain, colorectal, lung, and kidney cancers, to about 53,000 doses of Celegene’s Vidaza (azacitidine), which is used in the treatment of specific blood disorders, said Reuters Health. The study found that 70 percent of the doses were used for approved treatments; 30 percent were used off-label.
The researchers also reviewed off-label chemotherapies use and how those uses were supported by the National Comprehensive Care Network (NCCN), which publishes its own cancer care guidelines, said Reuters Health. The team learned that 14 percent of chemotherapies were prescribed off label and supported by the NCCN’s expert opinion; 10 percent were prescribed with no NCCN or FDA support. This is significant because, as Conti explained to Reuters Health, physicians will follow guidelines from expert organizations when insufficient data is available for the federal regulator to make a decision; for instance, when treating rare diseases that are challenging to research in a clinical trial, said Reuters Health.
Conti and her colleagues noted that some researchers have criticized NCCN recommendations, given both potential delays in releasing guidelines based on current data and possible conflicts of interests, Reuters Health explained. Of the $12 billion spent on chemotherapies in 2010, $4.5 billion was spent on off-label chemotherapies and $2.5 billion was spent on non-NCCN-supported uses.
“To me it’s a little troubling that so many drugs are given in areas where there is not a lot of data to back it up,” Dr. Nancy Keating, a cancer researcher not involved with the research, told Reuters Health. “The tricky thing is patients with cancer and their doctors are looking for anything with a benefit. So I think they’re sometimes willing to try things where there isn’t as much data as you would like,” said Keating, who is from Boston’s Harvard Medical School and Brigham and Women’s Hospital.
Conti said the research did not conclude if patients prescribed on-label chemotherapy fared better than those receiving off-label chemotherapy. “What our study basically does is highlight this proportion of use that is off-label and endorsed by expert opinion, or off-label and not endorsed by expert opinion,” Conti told Reuters Health. Conti pointed out that the study also revealed that the use of chemotherapies is driven by FDA approval and expert opinion, while treatments prescribed with no expert or FDA backing, may be over a lack of available treatments, said Reuters Health.