By Regina Nuzzo
Replacing the Pap Smear?
Researchers believe HPV testing may detect cervical cancer earlier than Pap testing
By Regina Nuzzo
For decades, Pap smears have been the standard method of screening for cervical cancer. However, the regimen of repeat testing over the years can be a burden in poor countries, which often lack sufficient health care infrastructure. A new study suggests that a better alternative might already exist. A single checkup for human papillomavirus (HPV) infection is enough to catch cancer early and save lives, the study found.
For a Pap smear, a clinician collects secretions from a woman’s cervix and analyzes the sample for the presence of abnormal cells. An HPV test also involves the analysis of cervical cells. But instead of looking for signs of cancer or precancer, it checks for the primary cause of cervical cancer: infection from one of the more than a dozen carcinogenic forms of HPV. Doctors can follow up positive results from either of the tests with a full exam to remove lesions and prevent cancer from developing.
The new study, published April 2 in the New England Journal of Medicine, compared these screening methods in more than 130,000 healthy women in India between the ages of 30 and 59. Researchers randomly assigned women to a single round of one of three tests—a Pap smear, HPV test, or visual inspection of the cervix—or to the current standard of care in India, which involves little screening. Researchers followed the women for eight years.
The HPV test significantly beat out a single Pap smear or visual inspection, results showed. Not only did HPV testing enable doctors to catch lesions and cancer earlier, it also was associated with a reduction in the overall death rate from cervical cancer, says radiation oncologist Rengaswamy Sankaranarayanan at the World Health Organization’s International Agency for Research on Cancer in Lyon, France, who is the lead author of the study. “HPV screening is probably more sensitive than the other tests in finding potentially malignant precancerous lesions,” he says.
Pap smears require repeated testing at least every few years to catch new abnormal cell growth. In comparison, a single HPV test can provide substantial benefits, Sankaranarayanan says. But HPV screening programs should focus on women 30 years and older to minimize the number of necessary medical visits, he says. That’s because women typically become infected with HPV through sexual intercourse early in their lives and fight it off—and so it is usually linked to cervical cancer only if the infection persists for a decade or so. American Cancer Society guidelines now say that women over 30 with average risk may get screened every three years with both a Pap test and an HPV test, as an alternative to getting a Pap test every two or three years.
Cervical cancer is one of the top three leading causes of cancer deaths in women worldwide. Out of the roughly half-million new cases diagnosed every year, 80 percent are in developing countries. And because the disease affects women at a young age—the median is 48—its impact on families worldwide is particularly devastating, says medical epidemiologist Mark Schiffman of the National Cancer Institute.
In the U.S., people in many communities also lack easy access to regular Pap tests, says cancer epidemiologist Electra D. Paskett at Ohio State University in Columbus. Women in Appalachia, rural Alaska and migrant communities, for example, have disproportionately high rates of cervical cancer and could benefit from HPV screening. “This kind of gynecological care has tremendous potential in the United States, too,” Paskett says.