Experts weigh best use of cervical cancer screens

Testing Pap smears that turn out to have "atypical squamous cells of undetermined significance" for human papillomavirus and only then referring women who have a positive result for colposcopy is a cost-effective practice, according to a study published in the Jan. 18 Journal of the National Cancer Institute.

"HPV testing identifies the largest percentage of women who need follow-up at a reasonable cost," said Shalini L. Kulasingam, PhD, lead author and assistant research professor at the Duke University Center for Clinical Health Policy Research in Durham, N.C.

But while HPV testing has become a more common part of cervical cancer screening, experts say the need for its use is far from clear-cut. Most guidelines indicate it's an acceptable option, as are colposcopy or repeat cytology, for this patient group. Still, determining cost effectiveness does not settle the question of how it should be used.

"It's a reasonable triage strategy from a cost point of view," said George F. Sawaya, MD, director of the Cervical Dysplasia Clinic at San Francisco General Hospital. "But this can be much more complicated than people appreciate."

For HPV testing to be the most cost efficient, it must be conducted on any Pap smear with certain results, and experts are concerned women might not have the opportunity to give fully informed consent.

"Since there are alternative strategies that are just as good, women should be involved in the discussion to be tested," said Dr. Sawaya, who is also an associate professor in obstetrics and gynecology at the University of California, San Francisco.

Physicians complain that because the public's knowledge of HPV is lacking, explaining the test's meaning and results can be time consuming.

"What I find with HPV testing is that patients need 15 or 20 minutes of explanation. ... They want to know about partner transmission and 'how did I get this,' when there's no way of knowing," said Joy Melnikow, MD, MPH, who wrote the accompanying editorial and is a professor in the Dept. of Family and Community Medicine at the University of California, Davis.

Quality of liquid-based cytology

This "reflex testing" also requires that initial screening be done with the newer liquid-based Pap test. Its use is not without controversy.

A study published Jan. 14 in The Lancet by researchers at the School of Public Health at the University of Sydney, Australia, found there was no evidence liquid-based cytology was any better than the traditional version, despite being more expensive.

"I have to compliment the company for doing such a great sell on it," said Sandra Sulik, MD, associate professor at State University of New York Upstate Medical University in Syracuse, N.Y. She has authored analyses with similar conclusions, but she still uses the test regularly in her family practice. "We think we're getting a better test because it's easier for the cytologist to read, but it doesn't pick up more cervical cancers."

Officials with Cytyc Corp., manufacturer of ThinPrep, the most common liquid-based Pap test used in the United States, criticized The Lancet review because of data authors chose to include or ignore. "[Liquid-based Pap smears] are better for the detection of disease," said Ellen Sheets, MD, Cytyc's vice-president of clinical affairs. She said the test was particularly useful for specific populations.

Physicians who prefer the liquid-based test, the most commonly used form in this country, also responded that it is better because there are fewer unusable or contaminated samples. HPV testing also can be carried out, as appropriate, without having to call the women back for another exam.

"If you cannot do reflex testing, you're really losing a lot, and you need to do the liquid-based cytology to do the reflex testing," said Mark Spitzer, MD, professor of clinical obstetrics and gynecology at Weill Medical College of Cornell University in New York.

Experts point out the review did not say the liquid test wasn't better, just that there wasn't evidence to prove it was. This finding indicates the need for better studies rather than a return to traditional cytology.

"This uncovers the difficulties in designing quality studies," said Daron Ferris, MD, president of the American Society for Colposcopy and Cervical Pathology. "It might be quite reasonable to undertake such a trial that would help settle this issue once and for all."