Fact: One out of five deaths in the United States is due to cancer

- What is Cancer?

Cancer is a disease characterized by uncontrolled and excessive (radical) multiplication of body cells. Cells are the building blocks that form tissues, and these tissues are what make up the organs of the body. Normal cells grow and divide, generating new cells, as the body needs them. In cancerous cells, this orderly process is replaced by radical and unnecessary cell division. Cancerous cells join together as growths, called malignant tumors, which invade and destroy the surrounding normal tissue. Besides local growth, cancerous cells also have the ability to spread throughout the body through the bloodstream or lymphatic vessels (the clear fluid which bathes body cells). In most patients, the spread of cancers from their site of origin to distant organs is responsible for the deadliness of malignant tumors.

The transformation of a normal cell to a cancerous one is only partially understood. The key to understanding the process of malignant transformation lies in the operation of the genetic material, or DNA (deoxyribonucleic acid), of the cell. DNA serves as the computer program that directs all cellular function and commands new cell replication and growth. When a cell becomes malignant, the process of self-replication (mitosis) is interrupted as cancerous cells reproduce almost continuously. Cells also become anaplastic (when cells revert to a primitive and unspecified form). Their DNA stops making the normal codes that allow cells to carry on healthy behaviors, and instead lead to movement of cells, invasion of adjoining tissues, and metastasis (spread into other areas). Often, the changes in DNA that result in malignancy occur as the result of environmental factors, such as infection, toxic chemicals (asbestos), sunlight, and other sources of injury. Once these changes are established in a cell, they are passed on to its daughter cells, thus leading to the cellular mutation (alteration) and the malignant growth we call cancer.

- Characteristics of Tumors

Tumors (also called neoplasms) are masses, or growths, that arise from normal tissue. They may be either malignant (progressive and life-threatening) or benign (nonprogressive and not life-threatening). Some of the differences between benign and malignant tumors are:

1. Benign tumors are nonprogressive and not life threatening. Malignant tumors are progressive and life threatening.
2. Benign tumors grow slowly, and malignant tumor cells multiple rapidly.
3. Benign tumors are often encapsulated (contained within a fibrous capsule or cover), so that the tumor cells do not invade the surrounding tissue. Malignant tumor growth is usually invasive and infiltrative, extending beyond the tissue or origin into adjacent organs.
4. Benign tumors are composed of highly organized and differentiated (specialized) cells, which closely resemble normal, mature tissue. Malignant tumors are composed of cancerous cells that resemble primitive cells that do not have the capacity for mature cellular functions. This characteristic of malignant tumors is called anaplasia. Anaplastic cells lack an orderly arrangement; instead, the tumor cells are found piled one on top of the other in a disorganized fashion.
5. Benign tumors do not spread to form secondary tumor masses in other places in the body. Malignant tumors, however, can detach themselves from the tumor site, travel through the bloodstream and lymphatic system, and establish a new tumor site at a distant region within the body (such secondary growth is known as metastasis).

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