I'm Faith Lapidus with the VOA Special English Health Report.

Last week, we discussed new findings about the way cancer spreads from one part of the body to another. Now, medical researchers in the United States are beginning an effort to find the genes that cause cancer.

Experts say cancer is not a single disease, but more than two hundred different diseases. In each case, they say, uncontrolled cell growth starts with molecular changes at the genetic level. In some cases the cells metastasize, or spread to other parts of the body, making the cancer more difficult to treat.

The Cancer Genome Atlas project could lead to new treatments and possibly even new ways to prevent cancer. Officials of the National Institutes of Health have agreed to spend one hundred million dollars over the next three years. Depending on the results, the project may be expanded in the future.

Doctor Francis Collins of the National Institutes of Health announced the project last week. Half the money will come from the National Cancer Institute. The other half will come from the National Human Genome Research Institute, where Doctor Collins is the director.

The idea for the project came about after the successful effort to map the human genes. The Human Genome Project was completed in two thousand three.

Now scientists will use that same technology to search for the genetic changes that lead to cancer. But they say mapping cancer genes will be much more complex than the human genome project. The researchers will study hundreds of examples of tissue taken from cancerous growths.

Cancer is the second leading killer in most developed countries, after heart disease. But survival rates have improved with medical progress in finding, treating and preventing cancer.

Researchers have worked for years to find the many genetic changes involved in cancer. But so far they have found very few. Many researchers have called for a systematic way to study cancer.

Drugs have successfully blocked some cancer-causing genes. But experts say only a small number of people have the genetic conditions that the drugs target.

This VOA Special English Health Report was written by Cynthia Kirk. Internet users can learn more about the Cancer Genome Atlas project at the government Web site genome-dot-gov, g-e-n-o-m-e dot g-o-v. And our reports are online at voaspecialenglish. I'm Faith Lapidus.