Pap Smear or HPV Test: Which is Best?

Pap testing is still the preferred test of many doctors for finding signs of cervical cancer, or cells that may turn into cancer in the future. But a growing number of doctors are calling for the HPV test to be the new standard.

Three studies published in October 2007, two in the New England Journal of Medicine and one in Lancet, supported using the HPV test in place of or in tandem with the Pap.

Inherent in using the PAP test is the possibility of false positives -- when a test is abnormal but there is no real problem.

Up until recently, the options to rule out false positives were either to repeat the Pap in three to six months or perform a colposcopy. In that procedure, a specialist -- generally a gynecologist -- looks at the cervix with a microscope-like device and performs biopsies of any abnormal areas.

Now, an immediate and less invasive test can be performed: the Human Papilloma Virus (HPV) test. Its usefulness has just been confirmed in a large study funded by the National Cancer Institute.

In the study, published in the Journal of the National Cancer Institute, researchers looked at more than 5,000 women with abnormal Pap smears. The study correctly identified 96.3 percent of the women with atypical squamous cells of undetermined significance (ASCUS) who needed to go on to the colposcopy.

"These results indicate that HPV testing is a viable option for women and their doctors to consider when deciding what to do about ASCUS," said NCI's Diane Solomon, M.D., the study's lead investigator.

HPV testing cuts the number of women who need colposcopy in half, thus reducing costs, and the time women must spend in limbo worrying about a possible cancer diagnosis.

In addition to false positives, the PAP yields false negatives between 13% and 45% of the time. The HPV test yields false negatives only 5% of the time. Other doctors argue that the PAP produces fewer false positives. For now, the jury is still out on which test should be the standard.