Are Pap Smears on the Way Out?
The venerable Pap smear, which has been the only screening tool to look for cancer in asymptomatic women for many decades, now has a rival, a genetic test that looks for the viruses implicated in causing cervical cancer. Adding a new option seems a positive development. Yet some critics have opposed using the new test as a primary screening tool lest it displace the Pap test, which has been credited with cutting the incidence and death rate from cervical cancer sharply in recent decades. The Food and Drug Administration recently approved the new test, which detects the DNA of the human papilloma virus, or HPV, which causes almost all cases of cervical cancer. The test, developed by Roche, is performed on a sample of cells taken from the cervix. It identifies 14 types of HPV that pose the highest risk of causing cervical cancer. By contrast, the Pap test involves examining a cervical sample under a microscope to look for abnormalities that might be cancer or precursors of cancer. Which test is better? The F.D.A. made no comparative judgment. It simply said that a well-designed study by Roche provided reasonable assurance that the test was safe and effective when used as a primary screening tool. An advisory committee of experts had unanimously recommended that the F.D.A. approve the Roche test to be used for primary screening. The test has previously been used either in conjunction with Pap smears or as a follow-up test when the Pap results were ambiguous. A similar advisory committee in Australia has said that an HPV test would be more effective, save more lives and be just as safe as a Pap test. HPV testing has some advantages over Pap tests. The Roche study showed that it was better able to detect precancerous lesions and a better predictor of whether a woman who tested negative would remain free of lesions for the next three years. The HPV test is also more objective than Pap tests, which rely on the judgment of health professionals viewing slides under a microscope. However, a coalition of 17 consumer, women's and health groups opposed the approval on grounds that the new test had not been adequately tested, will create confusion and might lead to expensive, invasive, potentially harmful follow-up procedures. The HPV test can cost twice as much as a $40 Pap smear. The new test is not expected to replace Pap smears in the United States any time soon. Professional societies will first need to develop guidelines on when and how doctors should use it. But it is welcome news that an effective new screening test for cervical cancer is available should women prefer that option.