People participating in cancer drug trials aren't always given the most straightforward explanation of possible risks and benefits from invasive procedures that may be involved, according to a new study.
Biopsies of tumor tissue can help researchers figure out how well a test drug is working - but the invasive, sometimes painful procedures are typically of little benefit to study participants themselves.
The new findings show more than five percent of biopsies in such trials may result in complications, but that informed consent documents spend less time explaining those risks than they do for simple blood draws, which are much less invasive.
"Most of these procedures don't have any therapeutic value for patients, they are burdensome, they're painful and they carry risk," said Jonathan Kimmelman, from the Biomedical Ethics Unit at McGill University in Montreal, Canada.
"Before you do a procedure like that on patients, you really want to have their adequate informed consent," Kimmelman, who wasn't involved in the new study, told Reuters Health.
"The only reason (patients) should submit to them is to contribute to science in some way," and not with the hope the biopsies will help them get better, he said.
For the new study, researchers from the University of Texas MD Anderson Cancer Center in Houston reviewed 57 cancer trials by their institution that involved tumor biopsies for study subjects and were conducted in 2005 through 2010.
In 38 of those trials, a biopsy was mandatory for all participants, often as a way for researchers to tell if the drug in question had worked as intended. In some other cases, biopsies were used as pre-study checks to see if patients had the right type of tumor for a certain targeted drug.
Lead author Dr. Michael Overman and his colleagues found almost all informed consent documents didn't specifically address the research alternatives to biopsies or the lack of likely benefits for patients themselves. The average document had just 39 words addressing the potential risks from study biopsies, compared to 48 words for blood draws.
In those trials, 576 patients had a total of 745 tumor biopsies - including lung, liver and head and neck biopsies. Thirty-nine of those resulted in complications, such as lung air leaks and bleeding, and six in major complications requiring patients to be hospitalized or to get further surgery, according to findings published Monday in the Journal of Clinical Oncology.
Overman said one of the problems has been that until now, there hasn't been enough available data for study investigators to give patients a reliable estimate of their chance of a biopsy-related complication.
"The informed consent documents that are used are not always as clear as they could be," Kimmelman said.
He added that not all cancer studies requiring biopsies are of the highest quality. And some don't make it into the published scientific literature, where they could potentially help determine if a drug is approved or could guide treatment decisions for future patients.
"I think a lot of patients understandably think that when they're volunteering for these studies they're giving tissue for what is cutting-edge science, and sometimes that's true, but not always," Kimmelman said.
Both researchers agreed that as more targeted drugs are designed for patients with very specific types of cancer, research biopsies will become increasingly necessary to determine how well those drugs are working on the tumor itself.
"I think giving biopsies is a good thing. I think you learn from it, but you need to do it in an honest fashion," Overman told Reuters Health.
Especially in early drug studies, the patients involved typically have few established treatment options.
"This is where we should say (to patients), ‘This is an experimental therapy, an experimental biopsy, and you don't have to do it,'" Overman said.