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Cancer protection from statins questioned
Source: (cancerfacts.com)
Wednesday, January 04, 2006
CHICAGO – Jan. 4, 2006 – The cholesterol-lowering drugs called statins do not appear to prevent cancer or cancer deaths, according to a pair of large studies analyzing data from multiple clinical trials and a large population study.
In a study led by Dr. C. Michael White, a team of researchers from the University of Connecticut and Hartford Hospital conducted, what is called a meta-analysis, on pooled data from 27 studies involving 86,936 people who participated in studies of statins. The results appear in today's Journal of the American Medical Association (JAMA).
"In our current meta-analysis, statins did not reduce the incidence of cancer or cancer death," the researchers wrote. "No reductions were noted for cancers of the breast, colon, gastrointestinal tract, prostate, respiratory tract, or skin (melanoma) when statins were used."
In a larger single population study by the American Cancer Society, Dr. Eric Jacobs's team analyzed the results of data collected from 132,136 men and women in the Cancer Prevention Study II Nutrition Cohort to see if there was any link between the drugs and colorectal cancer. A report on that study appears in today's issue of the Journal of the National Cancer Institute (JNCI).
"Our results do not support the hypothesis that statins, as a class of drugs, strongly reduce risk of colorectal cancer," the authors of the ACS study concluded.
The JAMA study pooled data from 27 clinical trials conducted previously over the past 40 years from 1966 through July 2005. The individual trials were large comparison trials aimed at determining the cholesterol-lowering benefits of statin drugs. The authors of the JAMA meta-analysis selected only those statin studies that involved simvastatin (Vytorin® and Zocor®) or pravastatin (Pravachol®).
Among the 27 published clinical trials that met their criteria for inclusion, the researchers found 20 studies that included data on cancer incidence and 22 studies that included data on cancer death. The individual studies included cancer monitoring due to early concerns of cancer risk for the new drugs.
While the individual trials showed substantial benefits in terms of reducing the incidence of heart attack and stroke, long-term follow-up of these patients showed no such benefit in terms of cancer.
In the JNCI study, Jacob's team examined the association between use of cholesterol-lowering drugs and colorectal cancer incidence among 132,136 men and women who took part in a long-term nutrition study.
They found a total of 815 cases of colorectal cancer among study participants during follow-up from the date of completion of a study questionnaire in 1997 through Aug. 31, 2001. After accounting for other factors, they found no affect on the incidence of colorectal cancer or survival either among current users of statins or among current users who had been taking the drugs for more than five years.
Eight smaller studies had previously found no association between statin use and colorectal cancer. Those studies however, did not look at long-term use of statins.
The Molecular Epidemiology of Colorectal Cancer, a large study conducted in Israel, however, did look at long-term use of statins and colorectal cancer. It included 1,953 patients diagnosed with colorectal cancer between 1998 and 2004 and 2,015 participants who did not have colorectal cancer. The MECC study found that statin use of more than 5 years was associated with a 47 percent reduction in risk of colorectal cancer.
The JNCI authors could not explain the difference in the results of the two studies, but noted that their study did not look at statin use specifically, rather all cholesterol-lowering drugs in general were included. Nevertheless, the authors did not think this would be enough to explain the differing results.
"However, such misclassification appears unlikely to have obscured a strong reduction in risk," the authors wrote. "If using statins for 5 years or more caused a 47 percent reduction in risk, we would have expected to observe a 25 percent reduction in risk (in our study) equivalent to a rate ratio of 0.75, which is not consistent with our observed risk estimate."
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