VOA慢速英語:Traditional Test for Cervix Cancer Being Used to Test for Other Cancers
By VOA
11 February, 2013
This is SCIENCE IN THE NEWS, in Special English. I'm Kelly Jean Kelly.
And I'm Avi Arditti. Today, we tell about a new way to test for cancers of the female reproductive system. We tell how a diabetes drug can help ovarian cancer patients. And we report on a finding that overweight people have a lower risk of death than those of normal weight. We also tell about a proposal to store documents, videos and other information in genetic material.
The Pap smear has long been the traditional test for cancer of the cervix, the muscular opening of the uterus. But it now is becoming a way to test for other cancers in women.
Scientists have developed a combination Pap test that also looks for two other hard-to-find cancers of the female reproductive system. The researchers created a method of testing that uses the Papanicolao or Pap smear test. They expanded the Pap smear to look for the genes linked with ovarian cancer and cancer of the endometrium.
In the United States, these two cancers are found in about 70,000 women every year, killing about one-third of them.
There are currently no tests to identify the two cancers. But scientists found that abnormal DNA is released from endometrial and ovarian tumors. This genetic material can be found among healthy cells in fluid taken from the cervix.
Using genetic maps, the researchers identified 12 of the most common mutated genes in both cancers. They used the new PapGene test to study cervical cell samples from 24 women. The test correctly predicted that all the women had endometrial cancer. But the test was less successful in predicting the presence of ovarian cancer.
Isaac Kinde works for the Sidney Kimmel Comprehensive Center at Johns Hopkins University in Baltimore, Maryland. He says the PapGene test identified only nine of 22 ovarian cancers in patients with the disease. He says ovarian cancer may be more difficult to find because of where ovaries are found in women.
"I think the most likely explanation for the result that we got is the fact that a cancer cell has to travel farther away from the ovaries to get to the cervix."
Isaac Kinde says his team is working with other researchers to make the PapGene test more sensitive in the recognition of ovarian cancer.
The Johns Hopkins team worked with researchers from Memorial Sloan-Kettering Cancer Center in New York City and the University of Sao Paulo in Brazil. Their findings appeared in the journal "Science Translational Medicine".
The survival rate for women with ovarian cancer is not good. Only about 50 percent can expect to survive the disease for five years. But researchers say the chances of living five years are better if women with ovarian cancer are also taking a common diabetes drug.
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| Cervical Cancer |
The researchers work at the Mayo Clinic in the American state of Minnesota. They found that 67 percent of ovarian cancer patients who were taking the drug metformin live five years or more after the discovery of their cancers. That is much better than the survival rate for those women who were not taking the drug.
Sanjeey Kumar is a cancer specialist with the clinic. He says researchers are not sure how metformin extends the life expectancy of some ovarian cancer patients. But he says they have theories:
"Such as acting through stem cells, cancer stem cells, or depriving the cancer cells of energy supply or glucose."
Stem cells are able to become any kind of body tissue. In the ovaries, stem cells produce normal ovarian cells. But the influence of some genes can turn stem cells into deadly cancer.
Metformin has been shown to prevent heart disease in people with diabetes. The drug reduces harmful levels of bad cholesterol and blood fats known as triglycerides in type-two diabetics. Doctors can also use metformin to treat a condition known as polycystic ovarian disease.
In the Mayo Clinic study, researchers compared the survival of 239 ovarian cancer patients. Sixty-one of the women were taking metformin. The drug was not given to the other women.
The researchers found that women taking metformin were nearly four times more likely to survive at least five years than the women not taking the drug.
There are few treatments for ovarian cancer, which has proven resistant to chemotherapy drugs. Sanjeey Kumar suspects that someday metformin will be given to women with the disease to improve their chances of survival.
The results of the study were published in the journal "Cancer".
New research shows that overweight or even mildly obese people have a lower risk of early death than people considered of normal weight. Researchers examined the results of 97 studies. Most of the studies were less than 10 years old. They included almost three million adults from around the world.
The researchers work at the National Center for Health Statistics, part of America's Centers for Disease Control and Prevention.
They found that people who are considered overweight or slightly obese were five to six percent less likely to die from all causes than people of normal weight. People with higher obesity ratings, however, had almost a 30 percent greater risk of death compared to normal-weight individuals.
Katherine Flegal was the lead author of the study. She says she was not surprised that overweight people would not have a higher risk of death. But she says the difference in death rates appears to be small between normal-weight people and those who are overweight or mildly obese.
The study has raised new questions about "body mass index," or BMI. This is a measurement of body fat as a ratio of height to weight. BMI guidelines were used as a basis for the study. In recent years, many health experts have promoted body mass index as a way to predict the risk of health problems. But a person's BMI can be misleading in some cases.
Steven Heymsfield is the executive director of the Pennington Biomedical Research Center in Baton Rouge, Louisiana. He says people can be physically fit and in good health, but might weigh more because they are more muscular.
Still, Dr. Heymsfield says people should not think gaining extra weight is OK just because of the new findings. He says being at a healthy weight lowers the risk for heart disease and diabetes. He and a colleague wrote an editorial that appeared along with the study in the Journal of the American Medical Association.
"Friends, Romans, countrymen! Lend me your ears."
"To be, or not to be. That is the question."
"This above all, to thine own self be true. And it must follow, as the night the day, thou canst not then be false to any man."
These words were written nearly 500 years ago. They are said to be the work of the English poet and playwright William Shakespeare. Many people consider Shakespeare to have been the best writer of all time. Far into the future, students of literature will read his words and praise the "Bard of Avon." But they will need our help to make sure that his words and thoughts survive.
Old paper falls apart as the years go by. Water, dryness and some kind of light are the enemy. When computers were invented, some people thought they had the problem solved. "Just make it digital," they said, "and it will last forever." But digital data is just a small amount of electricity that could be canceled by accident. CDs and DVDs could be ruined by heat. No, we need something better: Something that can store huge amounts of words, and pictures, and movies ... and do it all in a very small, safe place.
The answer, scientists say, may be based on DNA, deoxyribonucleic acid, found in the human body. Researchers at the European Bioinformatics Institute in England are making their own DNA and using it to store information. If their experiments prove successful, the researchers may be able to store one million CDs on something the size of your little finger.
The English scientists say that all you have to do is keep the DNA in a cold, dry and dark place. We know it works because scientists have recovered DNA from the bones of animals dead for thousands of years. It seems that putting the information into the DNA is the hard part. If the data is entered, or encoded, correctly, it will last for a long, long time. It then can be taken out in a usable form with 100 percent accuracy.
Using DNA for storage can be pricey. But scientists expect the cost to be much less as more experiments are done. They say that they might even be able to encode DNA with "zettabytes" of information. That, they say, is enough to save all the information that now exists ... on Earth!
The study about using DNA to store digital data appeared in the journal "Nature."
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