What is Cancer - What is Cancer

What is Cancer?
The human body is made up of billions of cells. Normally, cells function for a while, then die and are replaced by new cells in an orderly fashion. This results in an appropriate number of cells that are organized by the body to perform specific functions.
Tumors
Occasionally, however, cells are replaced in an uncontrolled way and are unable to be organized by the body to perform their normal function. As a result, there is an abnormal growth of cells that form a tumor. There are two kinds of tumors: malignant tumors (cancerous) and benign tumors (noncancerous).
Because of their increasing size, benign tumors squeeze surrounding parts of the body and expand into nearby areas. This can cause pain and interfere with normal function, but it is seldom life-threatening.
Malignant tumors can cause pain and interfere with normal function, but they can also cause other systems in the body to act abnormally. Malignant tumors can invade nearby groups of cells or tissues, crowding out and destroying normal cells.
Lymph Nodes
Cancer cells can also break away from the main or primary malignant tumor and travel to other parts of the body. The body fluids, that can carry cancer cells from the primary tumor to other parts of the body are the blood and the lymph.
Lymph is a nearly clear fluid that drains waste from cells. The lymphatic system transports fluid through vessels and into small bean-shaped structures called lymph nodes.
One function of lymph nodes is to filter unwanted substances, such as cancer cells, out of the lymph fluid. However, if there are too many cancer cells, the lymph nodes cannot remove all of them.
Isolated or disseminated tumor cells are single or small groups of tumor cells that have been separated from the primary tumor and can be found in the blood, lymph, or bone marrow. They can develop into life-threatening metastatic disease if they are untreated.
Men have slightly less than 1 in 2 chance that they will develop some type of cancer during their lifetime. Approximately 77% of all cancers are diagnosed in persons aged 55 and older. The most frequently diagnosed cancer in men in the US is prostate cancer.1
For more cancer-specific statistics, please visit www.cancer.org.
References
American Cancer Society. Cancer Facts and Figures 2008. Available at: http://www.cancer.org/docroot/STT/content/STT_1x_Cancer_Facts_and_Figures_
2008.asp. Accessed April 14, 2008.