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Archived Comments for: A systems biology approach to invasive behavior: comparing cancer metastasis and suburban sprawl development

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  1. Cities as Cancer

    Warren Martin Hern, University of Colorado

    29 March 2011

    The provocative article by Ryan, et al [1] using a systems biology approach in comparing cancer metastasis with suburban sprawl development as a way of learning new strategies for understanding and treating cancer is an original and thought-provoking approach to a dread disease. The authors propose a hypothesis that making this comparison can be "instructive."
    There are many kinds of cancer, and oncologists are always open to new ways of seeing and treating these illnesses.
    The authors correctly point out that there are certain analogies between invasive suburban sprawl and cancer metastases, and they draw comparisons between the specific factors impelling uncontrolled urban growth and the biological markers (such as the loss of p53 function) that trigger malignant growth in cells and tissues. It remains to be seen whether the analogous specific remedies for uncontrolled urban growth desribed by the authors can be applied successfully by oncologists for the benefit of a patient suffering a malignant disease. It does not appear that the authors have yet presented a testable or falsifiable hypothesis that can be refuted.
    The authors and I have looked at many of the same data and images and have arrived at different conclusions.
    As a public health physician studying urban geography in 1969, I was struck by the stunning similarity between images of the growth and invasiveness of cities over time and the images of malignancies that I had seen as a medical student. But I saw these patterns in relationship to other characteristics of the human population: rapid, uncontrolled growth, invasion and destruction of ecosystems adjacent to human communities, and distant colonization (metastasis) throughout all of human experience. These are all, at a different scale, diagnostic features of malignant tumors. A fourth characteristic, "de-differentiation," refers in cancer to the loss of specific cell and tissue appearances and distinctiveness. The squamous cells lining the alveoli of the lungs are completely different in appearance from the secretory cells lining another organ, and these are different from the cells of the liver, brain, or muscle or the specialized cells of any other tissue. In cancer, these distinctions disappear, and the "de-differentiation" results in undifferentiated cancer cells that don't look like the original tissue or anything else except other cancer cells. There are many examples of "de-differentiation" in human activities, but the most obvious is that all human communities are increasingly becoming undifferentiated from each other in size, appearance, morphology, function, and energy flows. I began pointing out these similarities between the human population and a malignant process in my first publication on this subject [2], which was illustrated with side-by-side images of malignant tumors and cities. In my most recent paper, "Urban malignancy: Similarities in the fractal dimensions of urban morphology and malignant neooplasms" [3], cited by the authors, I directly compared these two phenomena in many ways starting with the use of fractal geometry by both urban geographers and oncologists to study their subjects. Both use the same tools and get much the same results. The chilling observation is that an increased fractal dimension is often associated in cancer with increasing malignancy, and we are clearly seeing an increased fractal dimension of urban agglomerations over the past thousand years, especially since the appearance of walled cities in the middle ages.
    As I did, the authors cite Masek, et al [4], who reported the expansion of the Washington-Baltimore metropolitan area at the rate of 22 square kilometers per year from 1973 through 1996. They did not show, as I did in my 2008 paper [3], the startling image from that study showing the expansion of that urban agglomeration from 1792 through 1992, which clearly illustrates an invasive, malignant growth pattern over time.
    As I have shown in other papers [5,6], the comparisons between the human population and malignancies involves far more than the obvious phenomenon of urban sprawl, which is a late and very advanced manifestation of this long-term process. In fact, I have identified the human species as a global "ecopathological process" that is engaged in converting all plant, animal, organic and inorganic matter into human biomass or its adaptive adjuncts[2]. This is not an analogy. It is a diagnosis. You don't die from an analogy.
    A cancer continues until the host organism has ceased to function - it dies. In our case, the biosphere is the "host organism," and while the human species may not kill it entirely, we are in the process of altering its function in ways that will be terminal for us and a lot of other organisms.
    If cities look like metastatic cancers on the landscape, it's because they are.

    Warren M. Hern, M.D., M.P.H., Ph.D.
    Department of Anthropology, University of Colorado, Campus Box 233, Boulder, Colorado 80309-0233
    1. Ryan JJ, Dows BL, Kirk MV, Chen X, Eastman JR, Dyer RJ, Kjer LB: A systems biology approach to invasive behavior: comparing cancer metastasis and suburban sprawl development. BMC Research Notes 2010 3:36.
    2. Hern WM: Why are there so many of us? Description and diagnosis of a planetary ecopathological process. Population and Environment 1990 12:9-39.
    3. Hern WM: Urban malignancy: Similarity in the fractal dimensions of urban morphology and malignant neoplasms. International Journal of Anthropology 2008 23(1-2):1-19. http://www.drhern/pdfs/urbanmalignancy.pdf
    4. Masek JG, Vermote EF, Saleous NE, Wolfe R, Hall FG, Huemmrich KF, Gao F, Kutler J, Lim TK: A landsat surfance reflectance dataset for North America 1990-2000. IEEE Geoscience and Remote Sensing Letters 2006 31(1):68-72..
    5. Hern WM: Is human culture carcinogenic for uncontrolled population growth and ecological destruction? BioScience 1993 43(11):768-773.
    6. Hern WM: How many times has the human population doubled? Comparisons with cancer. Population and Environment 1999 21(1):59-80.

    Competing interests