What is Cancer?

Cancer is not a single disease. It is rather a heterogeneous group of conditions characterized by an abnormal cellular response during division. Cancerous cells divide rapidly and create tumors that take the place of regular cells and eventually rob healthy tissues of much needed nutrients.

Cells of advanced tumors can spread throughout the body, traveling to sites far away from where they originated. There they may settle and lead to the development of a new tumor, which, in turn, may grow and start spreading.

The most common cancers in the United States (estimates are from 2002) are:

• Breast cancer, with 205,000 estimated new cases each year, and 40,000 estimated deaths per year.
• Prostate cancer, with 189,000 estimated new cases each year, and 30,200 estimated deaths per year.
• Lung cancer, with 169,400 estimated new cases each year, and 154,900 estimated deaths per year.
• Colon and rectum cancer, with 148,300 estimated new cases each year, and 56,600 estimated deaths each year.
• Lymphoma, with 60,900 estimated new cases each year, and 25,800 estimated deaths each year.

Cancer Simplified

Normal cells grow, divide, mature and perish in response to a variety of factors, which can be both external and internal. A regular cell receives both stimulating and inhibiting signals, and the subtle balance between these two opposing forces is what leads to the normal growth and division of a cell within the body.

In a cancer cell, however, one or several of the signals have been disrupted, which causes the cell to proliferate at a rate (far) above average. Cancer cells lose their response to normal controls, which also causes them to gradually lose their normal shape and boundaries. This will eventually lead to the formation of a distinct mass of abnormal cells, which is referred to as a tumor. In general, a tumor can be one of two things. Either:

• The cells of the tumor remain completely localized. Then the tumor is said to be benign. Or
• The tumor cells are able to relocate to different locations and tissues within the body. Then the tumor is said to be malign.

Tumor cells that travel to other sites in the body, where they will establish secondary tumor, are said to have undergone metastasis.

It speaks for itself that these malign tumors are the dangerous ones, since they cannot be controlled in the way a benign tumor can. As benign tumors are limited to their present location, they can often be removed by surgery, whereas malign tumors occupy different sites in the body and potential surgical removal is never guaranteed to remove all of them.

(Estimate Source: American Cancer Society, Cancer Facts and Figures, 2002)