Is Vytorin Cancer Risk Real?
FAQ: Why Congress and the FDA Are Investigating Vytorin
Does Vytorin cause or promote cancer? continued...
Peto, a world-renowned expert in cancer epidemiology, took an unusual step. He got permission to take a look at the unblinded data from the two ongoing studies.
The result: Among the 20,000 patients in the two ongoing trials, there were 97 cancer deaths among patients taking Vytorin and 72 cancer deaths among control patients taking Zocor. However, there were about the same number of cancers in each group: 313 cancers in the Vytorin group and 326 cancers in the control group.
Peto dismissed the cancer-death disparity and focused on the number of cancers and when they occurred. If Vytorin was causing cancer, he said, the number of cases should have increased as patients stayed on the drug longer and longer. But this trend was not seen. Moreover, there was no increase in any particular kind of cancer -- just an overall increase in cancer deaths.
"Because these [trials] do not show excess cancer, because there is no time trend effect, these trials together do not provide any credible evidence of any effect [of Vytorin] on cancer," Peto said at the July 21 press conference announcing the SEAS findings. "The SHARP and IMPROVE-IT trials will have to run for some more years until they answer their main questions, but I think we should not be diverted by fears of cancer.
Richard H. Karas, MD, PhD, director of preventive cardiology at Tufts Medical Center, Boston, is convinced by the Peto analysis.
"In my opinion, looking at all of the information we have taken together, there is unlikely to be an increase in cancer with Vytorin," Karas tells WebMD. "The Peto analysis is well done and convincing. I think it is appropriate for the FDA to look at the data independently, but in the end, I think this is going to prove to be a non-issue."
But Steven Nissen, MD, head of cardiovascular medicine at the Cleveland Clinic and past president of the American College of Cardiology, feels very differently.
He says the Peto analysis is flawed because it looks at patients who have not been taking the study drug long enough to show a true difference. Indeed, the IMPROVE-IT trial is still recruiting patients. And Nissen strongly objects to "releasing clinical data at company-sponsored press conferences rather than via the scientific literature." (Merck tells WebMD the SEAS results were presented by the investigators and not by the company).