Are Cancers New Species?

The prevailing theory of how cancer develops is that tumors begin when mutated genes trigger uncontrolled cell growth. However, some cancer experts attribute cancer to disrupted chromosomes, which alter the balance of thousands of genes and produce cells with entirely new traits.

Cell biology
In order to make sense of this theory, it helps to understand basic cell biology. Each of the millions of cells in our body has a nucleus (a center) that contains DNA (deoxyribonucleic acid) molecules. DNA is packaged into thread-like structures called chromosomes.

Each DNA strand has genes, which contain genetic information. Genes are arranged in a linear pattern on DNA and are located at specific positions on particular chromosomes. Humans have 23 pairs of chromosomes (one from each parent) and each pair has recognizable characteristics. Disrupting chromosomes can lead to medical problems. Down syndrome is a common example the result of a disruption in chromosomes.

Cancer as a new species
Scientists who subscribe to this second approach of cancer development believe cancer arises when something disrupts chromosomes. This can damage them, causing them to duplicate or break, for example.  

Normally, disruptions in chromosomes would cause the cell to die. However, sometimes chromosomes can continue to divide, perpetuating the damage over time. This eventually creates new, stable chromosome patterns. In other words, a new species evolves that "doesn't depend on other cells for survival, doesn't follow orders like other cells in the body, and can grow where, when, and how it likes."

This theory helps explain why there's a long period between initial chromosome disruptions and when a patient develops full-blown cancer.

External environmental factors like x-rays, cigarettes, or radiation can disrupt chromosomes. For example, radiation significantly affects one particular type of chromosome damage, called translocation. Translocation occurs when a segment from one chromosome is transferred to a different chromosome or to a new site on the same chromosome. This leads to health problems, such as cancer. Genes are physically linked on chromosomes, so mutations could potentially be increased by "orders of magnitude" when we subject an organism to x-rays.

Some scientists believe these molecular rearrangements are the primary cause of cancers. In fact, they can link specific chromosome breakpoints to certain clinically defined cancers.

Understanding the true origins of cancer will hopefully lead to new ways to diagnose and treat the disease.



ScienceDaily. "Are Cancers Newly Evolved Species?" Web. 27 July 2011.