What are cancer cells?

Cancer describes any of a group of diseases characterized by the uncontrolled growth of cells that are destructive to the body's tissues and organs and can lead to death. Cancer cells form when normal cells are damaged and then multiply. It is not uncommon for a cell to form abnormally or become damaged, but in most cases the cell simply destroys itself in a process called apoptosis. The body's immune system thinks the cancer cells are normal cells, so the body's defenses will not attack them.

Most cancer cells multiply and remain localized, at least initially, forming a tumor, with one notable exception to this rule being leukemia. However, not all tumors are cancerous. Benign tumors are growths that may share certain characteristics with cancerous tumors, but are self-limited and nondestructive. They mostly don't come back after they are removed.

Malignant or cancerous tumors form as a result of a mutation or other damage to the genetic material of a normal cell. This occurrence often occurs in the body, but is almost always stopped when the damaged cell is killed, preventing the mutation from spreading. Strategic cell death or apoptosis is essential for the growth and survival of all living things. This fact becomes especially evident when apoptosis does not occur. The mutated cell survives to duplicate itself, and then these two cells divide, making more.

Other mutations can occur, and replication continues unchecked until a tumor forms. The normal process of cell division is not like the growth of cancer cells, which is not blunted by apoptosis. These cancer cells are somehow not recognized as harmful by the body's natural defense systems and are allowed to continue to multiply. If not removed, this group of cells can begin to destroy the tissue in which they were formed, as well as invade other areas of the body.

Cancer treatments focus primarily on removing and destroying the cancer cells themselves. They can range from surgery to remove tumors, to drugs that try to block the tumor's blood supply, to radiation therapy. Surgery is often the preferred method of removing localized tumors, and it is also necessary to remove a small margin of healthy tissue, as even a microscopic cancer cell can grow back into a tumor. Little is known about the reasons why mutated cells become cancerous, but a great deal of research is being done with the goal of more efficiently preventing and treating all types of cancer.

Go up