FREE ESSAY ON THE INS AND OUTS OF CANCER

THE INS AND OUTS OF CANCER

The Ins and Outs of Cancer
Cancer has affected the lives of each and every one of us alive today. Many people have
know someone with cancer, yet even those who haven't have been bombarded with constant
reminders of its terrible threat. Although cancer is often referred to as a single
condition, it actually consists of more than 100 different diseases, all characterized by
the uncontrolled growth, reproduction, and spread of abnormal body cells. All of these
diseases are individually unique, yet the basic processes that produce cancers are very
similar (Ruddon, 1995). The human body consists of over 30 trillion cells, living in a
complex, interdependent harmony. They regulate each other's proliferation; normal cells
reproduce only when instructed to do so by other cells in their vicinity. This constant
collaboration ensures that each tissue maintains a certain size and function that is
exactly what the body needs. Cancer cells, on the other hand, violate the entire process.
Not only do they ignore the body's controls on proliferation, they possess the ability to
invade nearby tissues, and may even metastasize - migrate and form tumors in distant
sites of the body. How do cancer cells achieve this? For decades, this question plagued
scientists everywhere. But over the last 20 years, scientists have uncovered a set of
basic principles that govern the development of cancer ( Brock, 1993). 
Within each cell lies a structure called a nucleus which contains strips of material
known as DNA (dioxyribonucleic acid.) Each of these strips is divided into hundreds of
genes, which are the codes and templates for all the functions of the human body. Each
gene specifies a sequence of amino acids that must be linked together to make a
particular protein; the protein then carries our the work of the gene. Two types of
genes, which are only a small fraction of the genetic material, play particularly
important roles in triggering cancer. Proto-oncogenes induce cell growth and
reproduction, while tumor suppressor genes inhibit it. Together, they carefully control
the proliferation of cells. However, if a proto-oncogene is mutated, it can become a
carcinogenic oncogene, driving excessive multiplication. Tumor suppressor genes, on the
other hand, contribute to cancer when they are inactivated by mutation (Ruddon, 1995). 
Luckily, cancerous tumors are not caused by one little mutation in one cell - they are
caused by multiple mutations in a number of the cell's growth-controlling genes. The
number of mutations necessary can be as low as two or quite high, depending on the
specific type of cancer. Generally, these mutations occur either from mistakes during
cell reproduction, or due to DNA damage caused by carcinogens such as tobacco, certain
poisons, and UV rays. So, why don't we all get cancer from these things right away?
Consider that one of your cells is damaged by poison and becomes mutated. In order for
this cell to turn into a cancer cell, the rest of the necessary mutations must also occur
in this very same cell. This in itself, is fairly unlikely. It normally takes decades for
an incipient tumor to collect all the mutations required for it's malignant growth, which
explains why the average age for cancer diagnosis is 67 (Ruddon, 1995). Why, then, do
some individuals contract cancer before the typical age of onset? In many cases, this is
explained by the inheritance of a mutation in a critical growth controlling gene.
Typically, this mutation would be a very rare event. However, in this individual, the
mutation is present in ALL the cells of the body, instead of in some randomly stricken
cell. So, the process of tumor formation skips it's first, slow step. No one can actually
inherit cancer; rather, they inherit a predisposition to develop a cancer, which is why
cancers do tend to run in families, but not all family members are stricken (Brock,
1993).
The outlook for people with cancer has improved steadily since the beginning of the 20th
century, when few cancer victims survived for very long. Today, 51% of cancer patients
survive for 5 years or more, and the American Cancer Society estimates that an additional
25% of cancer deaths could be prevented with earlier diagnosis and treatment (ACS
homepage). However, one in three people in the United States will eventually develop some
type of cancer, so routine screening for early detection should be an important part of
everyone's lives (Ruddon, 1995). The earlier cancer is diagnosed and treated, the better
the chance of it's being cured. Some cancers, such as breast and skin cancers, can be
detected by routine self-examination before they become too serious, while others are
only detected by more complicated methods. Either way, early diagnosis appears to be the
key to survival. 
Bibliography
Sources:
Ruddon, Raymond W. 1995. Cancer Biology, 3rd ed.
New York: Oxford University Press.
Brock, D.J.H. 1993. Molecular Genetics for the Clinician. 1st ed.
New York: Cambridge University Press.