SCIENCE IN THE NEWS #2126 - New Cancer Treatments

By Nancy SteinbachThis is Doug Johnson.And this is Sarah Long with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today we tell about new treatments for cancer. And we tell about new research with stem cells to treat other diseases.

Twenty-six-thousand cancer experts met recently in San Francisco, California to discuss the latest research against the deadly disease. They attendedthe yearly meeting of the American Society of Clinical Oncology. Oncology is the medical science that deals with the treatment of cancer. Many of the researchers presented the results of their work. Their research could change the way cancer is treated.

Medical researchers say cancer is the second leading cause of death in the United States and most other industrial countries, after heart disease. But cancer is not just one disease. It is a group of more than two-hundred diseases caused by a series of changed genes. These genes make cells reproduce out of control. This creates a growth called a tumor. Doctors usually treat cancer with an operation to remove the tumor. This is followed by radiation and chemotherapy drugs that destroy both cancerous and healthy cells.

Medical researchers say they are testing more than four-hundred experimental drugs to treat many different kinds of cancer. These treatments attack cancer at the genetic level. The new drugs block the chemical actions that cause normal cells to become cancerous. The experimental drugs appear to reduce or at least delay the growth of many kinds of cancer cells without damaging normal tissue.One of these experimental drugs is called C-two-two-five. It reduced the size of colon cancer tumors in about twenty-two percent of the people tested when used with chemotherapy drugs. The patients involved in the study had cancer that had spread to other organs and had failed to improve using other treatments.

A larger study of the drug will begin soon. It will test C-two-two-five in patients with colon cancer that has not yet spread to other organs. More studies will see if the drug can treat people suffering from other kinds of cancers.

Another new drug is called Tarceva. It showed activity against cancerous tumors of the head, neck, ovaries and lungs. A drug called Iressa showed good results in a study last year against lung cancer.

All these drugs are among a new group known as epidermal growth factor receptor blockers. The drugs interfere with the chemical activity that controls the lives of cells. The drugs attach to receptors on cells and block them from receiving messages that direct them to divide and become cancerous. Doctors say treatments that can successfully block these messages may someday change cancer from a killer into a disease that can be controlled for years.Earlier this month, the United States Food and Drug Administration approved one of these drugs. It was approved to treat one kind of leukemia, or cancer of the blood. It is called Gleevec. Scientists at the clinical oncology meeting reported that Gleevec has also shown good results treating a rare kind of intestinal cancer. It improved the conditions of about sixty percent of almost two-hundred people tested. Gleevec has been shown to reduce the size of cancerous tumors by blocking cellular messages that cause a cancer to increase. Another such signal blocker already in use is the drug Herceptin. It reduces the size of breast cancer tumors.These new drugs reduce the size of cancerous tumors. They do not make them disappear. Most of the drugs have been tested on only a small number of patients. Researchers say the drugs have fewer harmful effects on the body than traditional chemotherapy drugs. They also say that the experimental drugs can be used along with chemotherapy and radiation treatments.

Researchers say the new drugs can increase the effectiveness of these traditional cancer treatments. Studies show that the new drugs interfere with the ability of tumor cells to recover from the effects of chemotherapy or radiation.

Experts say more tests are needed before the experimental drugs can be proven safe and effective. However, most researchers say the drugs could be approved for use in the next few years.Other researchers at the clinical oncology meeting reported results of studies about a new medicine for men with severe prostate cancer. A drug called Atrasentan slowed the progression of cancer in men for whom no other drugs have been successful. In one study, the drug reduced the spread of the cancer into the bones. Another study showed that the drug lengthened the time before the sickest men felt pain in their bones. The researchers said they would expect the drug to have an increased effect if used before the cancer has spread.Still other scientists at the clinical oncology meeting reported about vaccines made from the cells of a cancer patient. These vaccines also have been shown to stop or reduce the growth of cancerous tumors. Sometimes the tumors completely disappeared.

These vaccines trick the body's defense system into attacking and destroying the damaged cells responsible for cancer. Studies have shown good results in people suffering lung and colorectal cancers. These studies are small, however. Researchers say more studies are needed before this kind of treatment can be used.The medical researchers at the clinical oncology meeting say much more work needs to be done before cancer can be cured. For example, they still do not know how long the new treatments will continue to delay the growth of cancerous tumors. They also do not know if the cancers will develop resistance to the drugs.

Some researchers say it will be difficult to cure the most common cancers. This is because these cancers have five or more genetic targets. They say a drug must be developed against each abnormal gene and used correctly together to be effective against the disease. Still, medical experts say the success of this new research has given them hope that attacking the genetic cause of cancer may cure the disease in the future.

((MUSIC BRIDGE))Two new American studies report major progress in stem cell research. Stem cells can develop into other kinds of cells and tissues. Scientists believe stem cells could become extremely important in the treatment of disease and injury.

Scientists at the National Institutes of Health near Washington, D-C carried out one of the studies. They took stem cells from unborn mice. The scientists then forced these embryonic stem cells to develop into several kinds of cells found in the organ called the pancreas. The cells then formed structures very similar to the pancreatic structures that produce insulin. Insulin is an important hormone that controls sugar levels in the blood. People whose bodies do not produce enough insulin have the disease diabetes.

The N-I-H scientists say the laboratory versions of the pancreatic structures acted like the real ones. They released insulin in the presence of sugar. The scientists injected the structures into diabetic mice. The treatment did not cure the mice of diabetes. But the scientists say the mice lived longer than they would have without the treatment.Scientists at Rockefeller University and Sloan-Kettering Institute in New York carried out the other study. The Rockefeller University researchers took a cell from a mouse tail and removed the genetic material. The researchers then removed the genetic material from a mouse egg. They put the genetic material from the skin cell into the mouse egg. In a few days an embryo began to form. Stem cells from embryos can develop into all kinds of cells and tissues.

The Sloan-Kettering scientists forced the mouse embryonic stem cells to develop into brain cells that produce the chemical dopamine. These are the brain cells that are damaged in people with Parkinson's disease. Now the Rockefeller University scientists plan to test the laboratory-made brain cells in mice that have Parkinson's disease.

This SCIENCE IN THE NEWS program was written by Nancy Steinbach and Caty Weaver. It was produced by George Grow. This is Sarah Long.And this is Doug Johnson. Join us again next week for more news about science in Special English on the Voice of America.

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