How Cancer Works - About Cancer

How Cancer Works by Dr. Jerry Gordon
HowStuffWorks

A diagnosis of cancer can be devastating. And there is good reason for this fear -- Cancer is the second leading cause of death in the United States next to heart disease, and will claim more than half a million lives this year.

The good news is that many forms of cancer can be avoided, and with early detection, a great number can be cured. In this article, we will look at the many faces of cancer so that you can understand the disease and its treatment, and also so that you learn about steps you can take to limit your exposure.

What we think of as "cancer" is actually a group of more than one hundred separate diseases. These diseases are all characterized by an abnormal and unregulated growth of cells. This growth destroys surrounding body tissues and may spread to other parts of the body in a process that is known as metastasis. You have probably heard of all of these different types of cancer:

* Skin cancer (squamous cell carcinoma and basal cell carcinoma being the most common)
* Lung cancer
* Brain cancer
* Breast cancer
* Prostate cancer
* Colon cancer
* Ovarian cancer
* Leukemia
* Lymphoma

There are many others as well.

Cancer can develop anywhere in the body, and at any age. Unlike infectious diseases such as AIDS, the flu (influenza), or tuberculosis, cancer is not contagious -- cancer is usually caused by genetic damage that happens inside an individual cell. Cells affected by cancer are called malignant cells. Malignant cells are different from normal cells in the body in that they divide (in most cases) much more rapidly than they should. This is important to know because many drugs used to fight cancer (antineoplastic or anticancer drugs) attack malignant cells during the active phase of cell division.

You may know someone who has had cancer, and his or her hair fell out during treatment. That happened because the anticancer drug(s) affected the normal hair follicle cells, which divide rapidly, as well as the rapidly-dividing malignant cells.

In the next section, we'll find out exactly what a tumor is.

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