A new study suggests that a single screening with a DNA test for HPV is more effective than all current methods of detecting cervical cancer. Some doctors say the easier test will replace Pap smears.
This isn't the first time we've heard that pap smears may be on their way out, but the results of the study of 130,000 women in India have put "another nail in the coffin" for Pap smears, as Stanford professor of gynecology Dr. Paul D. Blumenthal puts it in The New York Times. Scientists say that the new test could replace cruder screening methods in poor countries and allow women over 30 in wealthy countries to drop annual Pap smears and have a DNA test once every 3, 5, or 10 years.
The new study divided healthy Indian women between the ages of 30 and 59 into four groups. One group got the usual rural care, which is just advice to go to a hospital if they wanted screening. Another group got a "visualization" test, typical in poorer countries, in which a health worker looks at the cervix with a flashlight and swabs it with vinegar. Any white spots that develop may be precancerous lesions, so they are frozen off. A third group got pap smears and the fourth got a DNA test. For both tests cells are scraped from the cervix, but for the Pap test the cells are examined by a pathologist in lab and the results take days, while the DNA test can be read by a machine within hours.
After eight years, the control group and the visualization group had the same rates of cervical cancer and death, while the Pap-smear group had three-fourths the rates. Women who had the DNA test had half the rates of cancer and death, but none of the women who were negative on their DNA test died of cervical cancer.
Qiagen, the company that makes the DNA test, has developed a $5 version for use in poor countries that runs on batteries and doesn't require water or refrigeration. If a woman was tested just once every ten years and her results were negative, the chances that she would develop cancer would be low. In countries where women are hesitant to get pelvic exams, doctors say they test would still work if the women took the vaginal swab themselves.
Currently in poorer countries cervical cancer kills more than 250,000 woman a year. In the U.S. the cancer was a leading cause of death in the 1950s, but now it kills fewer than 4,000 women a year. In Europe most women don't start having Pap smears until 30, but the American Cancer society currently recommends that woman start yearly testing three years after they have sex, or no later than 21. After several normal results they may start testing only every three years. There are 150 strains of the human papillomavirus and cervical cancer is caused by only a few. Women pick up strains when they start having sex but most cases clear up on their own in about two years, and it's rare that the cancer would develop in under 15 years.
In 2002, the cancer society and the American College of Obstretricians and Gynocologists began recommending the HPV test as well and there is increasing evidence that the Pap smear is no longer necessary. "But we haven't been able to get doctors to go along," Dr. Debbie Salsow of the American Cancer Society said. "The average gynecologist, especially the older ones, says, ‘Women come in for their Pap smear, and that's how we get them in here to get other care.' We're totally overscreening, but when you've been telling everyone for 40 years to get an annual Pap smear, it's hard to change."
[Image via morgueFile.]