VOA慢速英语:HEALTH REPORT - Metastasis: How Cancers Can Spread Their Reach

This is the VOA Special English Health Report.

The word "metastasize" means to change form, state or position. It is not a word cancer patients want to hear.

Cancer can spread in a body two ways. As a tumor grows it may invade neighboring tissue or organs. Or, cancer can metastasize. This is when cancer cells break away from a first tumor and travel through blood vessels or the lymphatic system. The cells then grow in another part of the body. Not all cancers spread to other parts of the body after they are treated.

However, last month, two well-known Americans announced that their cancers had metastasized.

John and Elizabeth Edwards on March 22 as they announced that her cancer had returned, in an incurable form

Elizabeth Edwards, wife of Democratic Party presidential candidate, John Edwards, said her breast cancer had spread to her bones.

The next week the White House announced that Press Secretary Tony Snow's colon cancer had moved to his liver. The White House noted that the cancer was not in his liver but attached to it.

Missus Edwards' breast cancer was discovered in two thousand four. She was treated for several months with chemotherapy drugs to shrink the tumor. Then doctors removed it. The lumpectomy operation was followed with radiation treatments to kill any remaining cancer cells.

Tony Snow

Doctors removed Mister Snow's cancerous colon in two thousand five. He had chemotherapy for six months.

Most metastatic cancers are incurable. But most also are treatable. Chemotherapy drugs, radiation and other treatments can extend a patient's life.

Life expectancies differ depending on the kind of cancer, the affected organ and other issues. Some research shows that only about twenty-five percent of newly discovered metastatic breast cancer patients live for five years. The average life expectancy for metastatic colon cancer patients is about two years. Doctors say chances are worse for patients whose cancer is not found until after it has already metastasized.

But doctors say they can only guess how long any person may live with metastatic disease. In February, American and Canadian researchers announced a finding that may help in the fight against metastasis. They said the same enzyme that controls the ability of cancer cells to metastasize also controls the process that keeps them stuck tightly together.

And that's the VOA Special English Health Report, written by Caty Weaver.  I'm Steve Ember.