Countless people have had regular expensive testings and even organs removed
because, based on genetic testing, they've been told they are sure to get
cancer. Think about women having breasts amputated to avoid breast cancer in the
future, for example. Others live a life of worry and a feeling of impending doom
if they believe test results of "biomarkers" for specific diseases show sooner
or later they will probably get heart disease, dementia or some other potential
But it turns out, according to a new study, the research
associations between genes and other biomarkers
maladies is vastly overstated. Bottom line: were told you are more or less
doomed to eventually get a certain disease so you need constant
vigilance and testing?
Turns out, none of that may be true.
Research from John
Ioannidis, MD, DSc, an expert in scientific study design at the Stanford
University School of Medicine, shows clinicians may be making decisions for
inaccurate conclusions not supported by other, larger studies
one widely cited study links the BRCA1 gene mutation with colon cancer
; another links levels
of C-reactive protein
the blood with cardiovascular disease. Still another claims an association
between homocysteine levels with vascular disease. The trouble is, these
conclusions turned out to apparently be gross exaggerations. In a
statement to the press, Dr. Ioannidis claims these mistakes are "...the result
of statistical vagaries coupled with human nature and the competitive
nature of scientific publication."
His research paper
is published in the June
1 issue of the Journal of the American Medical Association
"No research finding has no uncertainty; there are always
fluctuations," Dr. Ioannidis stated. "This is not fraud or poor study design,
it's just statistical expectation. Some results
will be stronger,
some will be weaker. But scientific journals and researchers like to publish big
However, by publishing these popular "big associations",
the medical journals give the papers lots of publicity; the research papers are
cited over and over in the mainstream medical community (with little if any
critiques of the findings
). And soon they are
seen as proof linking a biomarker to a disease.
The result can be
unneeded testing, treatment, and more. It can also cause patients undue anxiety,
stress and fear for their future
Ioannidis and colleague Orestis Panagiotou, MD, from the University of Ioannina
School of Medicine in Greece, investigated 35 widely cited studies which
analyzed the relationships between biomarkers such as the presence of specific genes
or infections, levels
proteins and other
markers and the likelihood of developing conditions such as cancer and heart
They found that less than half of the biomarkers in these
studies had statistically significant associations with disease risk
in larger follow-up
studies. What's more, only one of every five of the original selected studies
increased a patient's relative risk
condition by more than 1.37, practically no risk at all (A relative risk of 1
means there is no difference between two groups).
In addition to
statistical findings that don't show up in additional, bigger studies, Dr.
Ioannidis said another problem is that researchers can also superimpose their
"Researchers tend to play with their data sets, and to
analyze them in creative ways. We're certainly not pointing out any one
investigator with this study; it's just the societal norm of science to operate
in that fashion. But we need to follow the scientific method through to the end
and demand replication and verification of results before accepting them as
fact," he stated.
Dr. Ioannidis, the C.F. Rehnborg Professor in Disease
Prevention at Stanford, outlined some of these same troubling research worries
years ago in a 2005 essay published in the journal PLoS-Medicine
entitled, "Why most published research findings are false."
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