New Debate Over Vytorin and Cancer
Data Are Reassuring, but Editor of Leading Medical Journal Says Drug Can't Be Cleared
Assessing Cancer Risks continued...
Yet Drazen and Steven Nissen, MD, chairman of the Cleveland Clinic's
department of cardiovascular medicine, point to a disturbing statistical
anomaly. If all the cancer deaths in the SEAS, IMPROVE-IT, and SHARP trials are
added together, there were 134 cancer deaths in patients taking Vytorin and 92
deaths in patients taking inactive placebo or the cholesterol-lowering drug Zocor.
That suggests a 45% increase in cancer deaths with Vytorin -- with a
statistical probability of 0.007, meaning the odds of it being a chance finding
are seven in 1,000.
Peto, a professor of medical statistics, says this isn't a fair analysis.
First of all, with all the thousands of clinical trials being done all over the
world, every year there will be false findings that have only a one in 1,000
chance of happening.
More specifically, he says, the reason for looking at the IMPROVE-IT and
SHARP results was to see whether the unexpected SEAS finding was true. Adding
the SEAS data to the other data pollutes the analysis.
"Suppose I have a freak result. To test whether it is true, I will check
out other data independently," Peto says. "What you cannot do is add up
the independent test with the test that got you alarmed in the first place. If
you include the test that got you freaky results in the first place, you will
have a freaky result in the end."
Waiting for More Data
Pedersen agrees with Peto that the Vytorin cancer link is likely a chance
finding. He notes that the SEAS trial looked at 1,250 disease categories and
saw "quite amazing single differences between the Vytorin and placebo
groups clearly arising by chance."
Nevertheless, Pedersen agrees with Drazen that the jury is still out until
more data become available.
"We should not just dismiss this and say it is just a chance
finding," Pedersen tells WebMD. "We should carefully collect data in
the IMPROVE-IT and SHARP trials to get more information."
There is an ongoing
FDA investigation of Vytorin data to see whether a safety warning is
appropriate. Meanwhile, Pedersen agrees with the American Heart Association and
the FDA advice not to stop taking any cholesterol medication without a doctor's
"My brother has been on Vytorin for three years," Pedersen says.
"I told him I would not be concerned about cancer risk, and that it is
better to have your cholesterol down."