The potentially negative side effects of cancer drugs are under-reported and may cause heart damage that puts patients at risk, according to Stanford University School of Medicine researchers.
In a report published online in the Journal of Clinical Oncology, the Stanford researchers called for urgent reforms to standardize measurements of the potential dangers of cancer drugs during clinical trials to prevent the publication of misleading results.
The researchers said such findings appeared in such prestigious scientific journals as the Lancet and the New England Journal of Medicine.
"It's a major issue when adverse events aren't being counted in clinical trials, and this has led to a profound under-appreciation of the risk for heart failure and other adverse cardiac events," said Dr. Ronald Witteles, a heart specialist.
Witteles and the report’s co-author – Dr. Melinda Telli, MD, of the Stanford Cancer Institute — said they have been seeing “surprising numbers” of patients with heart failure who were being treated with the cancer treatment sunitinib.
"That's what first raised our eyebrows," Witteles said.
The U.S. Food & Drug Administration approved sunitinib, sold by Pfizer Inc. under the trade name Sutent, for the treatment of kidney, pancreatic and gastrointestinal cancers.
The two researchers said they found drug labels noted the side effects of Sutent, but journal articles never discussed them.
"It didn't make any sense," Witteles said. "The labeling warned of a high incidence of heart failure during the clinical trials that was not even mentioned in the journal articles."
While the report focused solely on sunitinib, the authors said studies of other cancer drugs have similar problems and are prone to the same under-reporting of side effects.
"By no means are we trying to say that this isn't a useful drug," Witteles said. "This has been a truly revolutionary treatment for many different types of cancer. But what did happen, without a shadow of a doubt, was that the incidence of cardiac toxicity was misrepresented in the journal publications and, to this day, there is a real lack of recognition of this issue by practitioners.”