While cleaning up the files on my computer, I found this essay that I wrote two years ago. What better way to keep the file from being lost than to put it on the internet?
The assignment was pass or fail with no letter grades but with multiple chances to revise and resubmit. The professor told us to get started early because he had never had a student submit a passing paper on the first submission. Yada yada yada... here is the first of two essays that were accepted on the first submission. Second essay to come soon.
The process by which favorable genes allow an organism
to reproduce more successfully (natural selection) occurs in individuals on a
large scale but is also found in organisms on a very small scale. Since natural selection allows resistant
cancer cells to live and reproduce, new methods of cancer treatment are being
used.
The life cycle of
cancer begins in a manner similar to other organisms. According to the National Cancer Institute,
as cells age they reproduce as needed and eventually die. When cells begins to divert from this
process, “cells do not die when they should and new cells form when the body
does not need them” (National Cancer Institute, 2004, p.1). Eventually, a cancerous tumor will form. Without treatment, malignant tumors can continue
to grow and spread and may even take the life of the host party.
One of the classic
treatment options for cancer patients is chemotherapy, which the Cancer
Treatment Centers of America describes as “the treatment of cancer with drugs that can destroy cancer cells by
impeding their growth and reproduction” (Cancer Treatment, 2009, p.1). The goal is to completely eliminate all of
the cancerous cells. Unfortunately,
because of genetic variability, this does not always happen.
When organisms
reproduce, the biological information is not always passed on flawlessly to the
offspring; there may be variations in the gene structure. These variations,
however, are necessary for natural selection to occur. “The evolutionary significance of genetic
variability is its potential to fuel evolution as organisms change to differ
from their ancestors” (Hall and Hallgrimsson, 2008, p. 175). Without any variations, natural selection
could never occur. It is this
variability that allows either artificial or natural selection to select the
genes that give the organism an advantage.
Natural selection may play a negative roll in cancer
treatment. Some of the cells may contain
a genetic mutation which allows them to be naturally resistant to the treatment
drug. Continued treatment can even
encourage mutant-cell growth. The Wistar
Institute, a “nonprofit biomedical research institute” (Wistar Institute, 2010,
p.1), found that mutant cell reproduction can be “amplified in tissues with
repeated wounding, in which repeated cycles of cell death and proliferation
enable a mutant clone with a survival or reproductive advantage to expand”
(Merlo et al, 2006, p. 927). These cells
then reproduce, passing on the same drug-resistant genes to their
offspring. This would render the drug
useless once the tumor is composed of cells with the resistant gene. In order for cancer treatments to be
successful, a variety of treatments must be used. In addition, new and
innovative approaches are being developed to combat the cancer problem of
natural selection.
Carlo C. Maley, a researcher on a Wistar Institute
cancer study project, gave some ideas (Science Daily, 2009, p.1.) as to what
types of new treatment options are available to cancer patients. One idea is counterintuitive of the
traditional chemotherapy approach. Instead of killing the cancerous cells, the
benign cells in a tumor would be given a stimulus that would allow them to
survive better than cancerous cells.
This would allow them more access to the essentials of life, destroying
the malignant cells.
In a similar
approach, Maley says:
Another idea we're pursuing is what we call
the sucker's gambit. In this case, you
try to increase the fitness of chemosensitive cells so that they outcompete any
resistant cells that are in the tumor. And then you apply your chemotherapy. So
you sucker the tumor into a vulnerable state and then you hit it with your
therapy (Science Daily, 2009, p.1).
Due to past and current research, evolutionary
biologists must work together with cancer research teams in order to introduce
new and innovative approaches to the fight against cancer. But, “[n]o matter how we intervene in a
[tumor], some cells will grow back to fill that space” (Merlo et al, 2006,
p.933). As research continues to
increase our understanding of cancer and natural selection, we will be able to
use the natural processes of selection to our advantage.
Works Cited
Cancer Treatment Centers of America. 2009. Chemotherapy. In:
Treatments. Cancer Treatment Centers of America. Accessed February 8, 2010.
http://www.cancercenter.com/conventional-cancer-treatment/chemotherapy.cfm
Hall, B.K. and B. Hallgrimsson. 2008. Strickberger’s Evolution. 4th ed.
Jones and Bartlett Publishers, Sudbury, MA 760 pp.
Merlo, L.M.F., J.W. Pepper, B.J. Reid, and C.C. Maley. 2006. Cancer as
an evolutionary and ecological process. Nature Reviews Cancer (6)924-935.
http://web.ebscohost.com/ehost/pdf?vid=4&hid=8&sid=97e2bd82-d610-4614-b878-0815a4a12d7e%40sessionmgr12
National Cancer Institute. 2004. What is cancer?. In: Cancer Topics.
U.S. National Institutes of Health. Accessed February 8, 2010.
http://www.cancer.gov/cancertopics/factsheet/Sites-Types/metastatic
Science Daily. 2009. Does natural selection drive the evolution of
cancer?. The Wistar Institute. Accessed February 7, 2010.
http://www.sciencedaily.com/releases/2006/11/061117114616.htm
Wistar Institute, The. 2010. Overview. In: About Wistar. The Wistar
Institute. Accessed February 8, 2010.
http://www.wistar.org/about_wistar/overview.html