What are the causes of cancer?
There are some known causes of cancer and some that are unknown; scientists work around the clock, around the world to discover why people get the types of cancer they do. What we know can be divided into two main causes:
In some cancers it run in the family and if this is the case it usually means that you are more likely. The cancers that are known to be linked a genetic cause are breast cancer.
Some of the environmental things that are known to cause cancer are:
· Tobacco (chewable) or cigarette, cigar, sheesha and midwagh smoking
· Improper diet, excess body weight and alcohol abuse
· Excess UV radiation from the sun and/or tanning bed
These things in the environment cause cancer because they are carcinogens.
A carcinogen is a substance that causes cancer. We know that a substance causes cancer as we test it in the lab, observe the effects on other creatures etc. Carcinogens can be many things but may include substances such asbestos (used in construction) and pesticides (used to keep insects away by spraying plants).
There are many groups worldwide working hard to discover what and where these carcinogens are. The World Health Organization (WHO), or more specifically, the International Agency for Research on Cancer (IARC) is the establishment that finds and classifies these carcinogenic agents into groups based on their level of hazard. They are placed in categories according to how dangerous they are. For example:
· Group 1: Carcinogenic to humans
· Group 2A: Probably carcinogenic to humans
· Group 2B: Possibly carcinogenic to humans
· Group 3: Unclassifiable as to carcinogenicity in humans
· Group 4: Probably not carcinogenic to humans
The International Agency for Research on Cancer (IARC). Monograph: Overall Evaluations of Carcinogenicity to Humans. 2008 is Available at: http://monographs.iarc.fr/ENG/Classification/index.php. Accessed August 27, 2008. They have a complete list of known carcinogenic agents
What are cancer cells and how are they produced?
The body is made up of millions of normal cells. Cells make up organs that have everyday functions. Each cell is born with a role that keeps the body functioning properly and each cell dies when it grows old and fulfils its role. These normal cells, for genetic, environmental or sometimes unknown purposes, suddenly go out of control.
Some characteristics of a cancer cell include the ability to increase in number uncontrollably, induce the growth of blood vessels to supply nutrients to the growing cancer or tumor and spread to other parts of the body via the blood or lymph vessels.
As mentioned earlier, cancer cells are formed when normal cells accumulate mutations that cause an accelerated expression of certain proteins. These proteins cause proliferation (division) of cancer cells and inhibition (blocking) of our ‘police’ proteins. These ‘police’ proteins normally silence gene mutations and like traffic, regulate how a normal cell should die. P53 is a ‘police’ protein, the head of the police, which is found to be suppressed in many cancer cells; it is our ultimate protector against cancer. Smoking will instantly kill your P53.
Once a normal cell loses its ability to undergo cell death and continues to multiply rapidly, it becomes less and less differentiated and deviates away from its original function. This will eventually lead to the failure of the affected organ and subsequently the biological system.
Accelerated division of cancer cells increases the demand for nutrients in order for the cell to survive. Cancer cells have come around this dilemma by secreting chemicals that trigger nearby blood vessels to branch and form new vessels in a process called angiogenesis. Moreover, the newly formed blood vessels also serve as a transport system, which allows cancer cells to migrate to other organs. Spreading to other tissues, or metastasis, increases the chance of cancer cell survival even after treatment.
One might ask why our immune system does not fight cancer cells like it does with bacteria? The reason would be due to cancer cells being originally normal cells but ‘gone bad’. In addition, white blood cells recognize markers on the surface of normal cells that would indicate if the cell is a friend or foe. Since cancer cells were originally normal, their cell surface would resemble that of normal cells. Therefore, it is difficult for white blood cells to detect and defend the body from such abnormalities.