Cancer Treatment

Most people who develop cancer do not have inherited genetic abnormalities. Their genes are damaged after birth by carcinogens in their environment.

Scientists identify carcinogens by investigating unusually high cancer rates in groups of unrelated people. For example, scientists might notice that people in a particular job tend to get a certain type of cancer. Experts would then study the ability of chemicals or other substances encountered in that job to cause cancer in laboratory animals. If a high percentage of the animals develop cancer, researchers strongly suspect that the agent may also cause cancer in people.

Once a carcinogen damages a cell's DNA, the damage can be passed on to new cells that arise from division of the damaged cell. The changes are thus passed on to all the cell's descendants. Meanwhile, the descendant cells can acquire additional DNA damage that is also passed along. Experts think many cancers arise from such combined effects of several carcinogens.