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Dr. Marianne Berwick
The Population Dynamics of Cancer:
A Darwinian Perspective |
| Carcinogenesis can be interpreted as the consequence of
selection of mutated cells that occurs in a population of cells belonging to a multicellular
organism. The observed geographic distribution of cancer is attributable to environmental mutagens.
However, the rapid change in risk for some cancers after migration suggests that carcinogenesis
involves some late event that involves selection of cells already carrying mutations. A few examples
of such selective pressures include finasteride in prostate cancer, vitamin supplementation in smokers,
acquired resistance to chemotherapy, peripheral resistance to insulin, and sunlight and mutations in
melanoma. A "Darwinian" model of carcinogenesis suggests that prevention is more complex than avoiding
exposure to mutagens. Mutations and genetic instability can be already present at birth and can be
selected in the course of life if they increase survival advantage of the cell under certain environmental
circumstances. In addition, gene-environment interactions cannot be interpreted according to a simplified
linear model; experimental work suggests that a more comprehensive non-linear interpretation based on
the idea of "norm of reaction" is needed. |
| Dr. Marianne Berwick is Professor of Epidemiology and Chief of the
Division of Epidemiology, Department of Internal Medicine, at the University of New Mexico. She is also
the Senior Leader for the Population Science Program at the UNM Cancer Center. |
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