Researchers are proposing the use of sophisticated technology in poor countries to detect cervical cancer, the leading cause of cancer death among women around the world. Investigators found DNA testing in developing nations could save time and money as well as lives.
Scientists have little doubt about what causes cancer of the womb opening, or cervix.
"Almost every case of cervical cancer in the world is caused by one of 15 related types of human papilloma virus," said Dr. Mark Schiffman, an epidemiologist with the U.S. National Cancer Institute. He says the main culprits are human papilloma viruses, or HPV, types 16 and 18, which are sexually-transmitted.
In the West, rates of cervical cancer have dropped dramatically thanks to the Pap smear, a test in which a sample of cells taken from the surface of the cervix are examined under the microscope for pre-cancerous abnormalities.
At the time of the examination, the doctor also looks at the cervix to see if there are any suspicious sores.
If the testing comes back positive, a woman will make many visits back and forth to her doctor for treatment and follow up.
The same situation is not very practical, or affordable, in poorer countries. So, researchers at Harvard University School of Public Health in Boston looked at the use of DNA testing to identify women exposed to HPV 16 and 18 in developing nations.
"The new tests are molecular tests. They're either looking for the DNA of the virus or its RNA, which is what the DNA produces on the way to making enzymes that are the activity of the virus. So, the molecular tests are much more sensitive. They are much more likely to pick up a pre-cancer or a cancer, something that needs treatment, if it's there, than a Pap smear," Dr. Schiffman explained.
Harvard investigators assessed cervical cancer detection and treatment methods in India, Kenya, Peru, South Africa and Thailand. They found that the most effective screening test was DNA testing for HPV because women could be tested and treated on the spot.
Writing in the New England Journal of Medicine, the researchers report that women could be screened once or twice between the ages of 35 and 45, and then followed up with one or two visual inspections.
Investigators say the cost is considerably less than a western-style schedule of annual Pap tests, and DNA testing could cut in half the number of deaths from cervical cancer. Each year, a half million women are diagnosed with the disease.
In comments on the report, Dr. Schiffman says "screen and treat" centers using DNA testing are very appealing. "Given enough resources, one could go about methodically eliminating cervical cancer throughout the world," he said.
U.S. regulators are now considering whether to approve two vaccines that would prevent young women from getting HPV in the first place. So far, there's no way to treat the disease, which poses a bigger risk to older women.