by Ron Brown, Ph.D., author of The Body Fat Guide
"Ron Brown is a certified fitness trainer who doesn't have an inch of flab on his body. He'll tell you what you can do to become fit and trim too."
TALK TO AMERICA, Washington DC
Nightly News anchor Brian Williams led his March 20,
2012 broadcast with a story about research claiming that simple aspirin may
prevent cancer. One of several research studies found a cancer risk reduction of 25% in a
group of patients that took aspirin relative to another group that didnít take
aspirin. But Brian Williams doesnít seem to understand that the relative risk
reduction reported in the studies published in the Lancet for March, 2012 does not represent the actual or absolute risk
reduction of cancer in patients taking aspirin.
According to a BBC report of one study involving 78,000 participants, there were only nine cases of cancer for every 1000 participants who took aspirin compared to 12 cases for every 1000 participants who did not take aspirin. Comparing the groups, the aspirin group lowered the number of cancer cases by three. If you divide the case reduction in the aspirin group by the number of cancer cases in the non-aspirin group, 3/12, itís true that you get a relative risk reduction in cancer cases of 25% as reported in the media.
But remember, these figures are calculated per 1,000 participants in each group. The actual or absolute difference in the number of cancer cases between the groups is only three cases for every 1,000 participants. Thatís an actual reduction in cancer cases among participants taking aspirin of a paltry 0.3%! This is calculated as: 3/1000*100 = three-tenths of one percent! Most scientists would not consider such a small difference between groups to be statistically significant. In other words, there is a high probability that this small difference occurred in the study simply by chance rather than from the aspirin. In addition, as with all drugs, taking aspirin has adverse health effects.
Unfortunately, even many physicians, including NBC's Dr. Nancy Snyderman, do not appear to understand the difference between relative and absolute risk reduction figures. Manufacturers and treatment providers prefer using the more favorable sounding relative risk reduction figures to promote and advertise pharmaceutical and health products and services, from toothpaste to statins to chemotherapy to weight-loss supplements. It is vitally important that consumers are aware of this misleading practice in order to make better informed choices that affect their health. Whenever you read or hear the message, "Clinical studies show that (product name) lowered (symptom) by __%," you know you are usually hearing only the relative risk reduction figures of the studies while the absolute risk reduction figures often remain hidden.
Although Brian Williams was technically correct in reporting relative risk reduction results for aspirin reducing cancer, leaving out the absolute risk reduction figures in the study amounted to reporting a half-truth with highly misleading implications. Contrary to media reports, absolute risk reduction figures calculated from the study findings strongly suggest that aspirin does not prevent cancer! Got cancer? Take two aspirin and call me in the morning...if only it were true.