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Could
cancer be linked to lifestyle?
New
research in the cancer field indicates that
genetics may not play as large a role in
cancer risk as once thought. In fact, environmental
factors may be a more important contributor
to cancer risk than previously thought.
Lichtenstein et al. (2000) conducted a study
of 44, 788 twins in Finland, Denmark and
Sweden to assess cancer risk. Results indicate
that while genetics make a small contribution
to susceptibility to most types of cancer,
environment has a large role in causing
cancer. Most types of cancer showed little
impact of shared genes. Prostate cancer
is one of the cancers with the highest genetic
influence but studies have also shown a
large environmental component. Rates of
concordance were generally higher in monozygotic
twins than dizygotic twins, but even for
genetically identical twins, there was a
less than 15% chance of developing the same
cancer.
The authors acknowledge that this study
does not take into account specific types
and degrees of exposure to environmental
risks, such as tobacco use or diet, so issues
of gene and environment interaction cannot
be fully explored. But they also mention
that despite it's limitations, the Lichtenstein
et al. study provides "new and valuable
information for the nature-versus-nurture
debate."
Due to the influence of environment on cancer
risk, diet can either reduce or exacerbate
a genetic predisposition. There is evidence
that a diet high in fruit and vegetables
can protect against lung and possibly breast
cancer, and a diet that includes plenty
of vegetables protects against bowel cancer.
On the other hand, diets high in red meat
and alcohol may increase bowel cancer risk.
Breast cancer risk may also be increased
with alcohol consumption, and possibly red
meat. Products thought to protect against
cancer include fish (due to omega-3 fatty
acids or other unknown components), green
and oolong tea, and soy based products.
References
Lichtenstein, P., Holm, N.V., Verkasalo, P.K.,
Iliadou, A., Kaprio, J., Koskenvuo, M., Pukkala,
E., Skytthe, A., Hemminki, K. Environmental
and Heritable Factors in the Causation of
Cancer - Analysis of Cohorts of Twins from
Sweden, Denmark and Finland. NEJM. July
13, 2000. Vol343, No. 2.
Hoover, R.N. Cancer
- Nature, Nurture or Both. NEJM. July
13, 2000. Vol. 343, No 2.
Better Health Channel - Cancer and Food.
Last
Updated: April 5, 2001.
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