HPV test or Pap: Understanding the choices

Advertisements can be very persuasive -- whether they’re promoting a snack food, a toy or even a medical test. If you’ve watched much television lately, you may have seen a commercial touting the benefits of a relatively new screening test for cervical cancer. Its message is unambiguous: “A Pap test isn’t enough.”

The advertisement encourages women to get tested for human papillomavirus (HPV), the virus known to cause cervical cancer. The test looks for the presence of 13 types of “high-risk” viruses that cause more than 99% of cervical cancers.

But the test isn’t necessary or even appropriate for everyone.

For starters, women who have had three consecutive Pap smears showing no abnormalities face an extremely slim chance of developing cervical cancer, less than one in 1,000. So, for women who get regular pap smears, the test adds little beyond expense and additional lab work.

Further, the HPV test, when combined with the Pap smear, can sometimes create more problems than it solves.

“In the vast majority of patients, the results of the combined testing will be very straightforward,” says Alan Waxman, a professor of obstetrics and gynecology at the University of New Mexico’s School of Medicine. “But about 5% of patients are left in something of a dilemma.”

A Pap smear with mild abnormalities along with a negative test for HPV can leave a woman guessing if she has a problem; a normal Pap smear and a positive HPV test can cause her to wonder if problems are imminent.

For some, simply testing positive for HPV causes unnecessary worry. About 90% of women who become infected with HPV clear the virus before it causes problems. Even among those who develop a persistent infection, only a small fraction will develop cancer, and the HPV test does not differentiate those who will get it from those who won’t.

And even though the infection is common, learning that they have a sexually transmitted infection is emotionally upsetting for many people. In an article published last year in the journal Sexually Transmitted Infections, British researchers found that women who tested positive for HPV described feeling stigmatized, anxious and stressed; they also expressed concern about their sexual relationships and worried about disclosing the results to others.

For women who don’t get Pap smears regularly, combined testing with the Pap smear and HPV test does appear to offer a clear advantage. “A single Pap smear is not a very good test,” says Waxman. An isolated smear will identify only half to three-quarters of all women with precancerous or cancerous changes. The remaining women will receive false-negative Pap results, and their problems will go undetected.

Screening with both the Pap smear and the HPV test is more likely to identify a problem if one exists. A normal Pap smear and negative HPV test tells a woman that her risk of developing cancer over the next several years is exceptionally low; an abnormal Pap smear and positive HPV test, on the other hand, suggests that she is clearly at risk and that close follow-up is necessary.

“When I see a woman who hasn’t gotten regular Pap tests, I want the biggest bang for the buck and am more inclined to do both tests,” Waxman says.

In 2003, the American College of Obstetrics and Gynecology issued new cervical cancer screening recommendations that took HPV testing into consideration for the first time. For women younger than 30, the group now recommends annual screening with Pap smears alone and discourages the use of combined testing. While younger women are more likely to test positive for high-risk HPV types, these infections are highly likely to clear up relatively quickly.

For women older than 30, the recommendations are less clear-cut and endorse two approaches. Annual screening with the Pap smear alone remains a viable option. If three consecutive annual smears are normal, testing only needs to be performed once every two to three years.

Alternatively, HPV testing can be performed along with a Pap smear. Women with a normal Pap smear and a negative HPV test should then be re-screened with both tests every three years. If only one of the tests is negative, however, more frequent screening or follow-up testing will be necessary.

The 30-second television ad sponsored by the manufacturer of the HPV test, Digene, is a good one -- from a sales perspective at least. It makes a compelling argument for HPV testing. What it doesn’t tell you is just who should be persuaded.

--

Dr. Valerie Ulene is a board-certified specialist in preventive medicine practicing in L.A. She can be reached at themd@att.net. The MD appears the first Monday of the month.