Advances Enhance Accuracy and Convenience of Pap Tests

Every year, millions of American women have a screening test called a Pap smear to determine whether they are at risk for cervical cancer. It’s an important test: cervical cancer has no real symptoms in the early stages, yet when it’s detected early, it is one of the most treatable and curable of all cancers.

Historically, however, 5% to 10% of Pap smear lab results come back described as neither normal nor malignant, but are given a gray-area description such as atypical, abnormal, or inconclusive.

“It’s been a big problem,” says Michael R. Lund, MD, Assistant Professor of Obstetrics & Gynecology at the Medical College of Wisconsin. “Results and descriptions could vary from lab to lab. It made it difficult at times for physicians to know how to advise patients.”

Traditionally, when a Pap test came back with an “atypical” designation, the patient would routinely undergo additional Pap tests, often every 4 months, and sometimes other procedures. Cervical cancer was eventually ruled out in most cases, but only after the woman underwent the cost and inconvenience of follow-up tests – and weeks or even months of anxiety.

But that’s changing, Dr. Lund says, thanks to 3 factors: new methods for taking Pap smears, new national guidelines for interpreting Pap results more clearly, and better understanding of the causes of cervical cancer. As a result, doctors can determine more precisely whether their patients are likely to develop cervical cancer and whether they need to undergo further testing. For patients it means more convenience and greater peace of mind.

New Test Methods
With the new methods for collecting cervical samples, Dr. Lund says, tissue samples are transferred to a liquid solution, rather than to a slide, for laboratory analysis.

“The liquid Paps generally pick up more abnormalities than conventional Paps,” he says. “The lab can better eliminate mucus and other debris than before, and if the test has to be repeated, it can be done without the woman having to have another Pap smear taken.” The liquid Pap method has been used by Froedtert Hospital laboratories for the past 1-2 years, he said. At Froedtert, the liquid Pap costs the same as the former method did when slides were analyzed, although that might not be true everywhere.

Improved Pap Test Descriptions
To promote better communication between laboratory and treating physicians, new guidelines, called the Bethesda System, were developed at a conference last year sponsored by the American Society for Colposcopy and Cervical Pathology. Participants included representatives from approximately 40 professional groups, including the American Cancer Society and the American College of Obstetricians and Gynecologists. Recommendations were announced in April in the Journal of the American Medical Association (JAMA).

“It’s the third generation of the Bethesda System recommendations,” Dr. Lund says. “The goal is to continually refine our terminology to eliminate problems.”

The Bethesda System uses a uniform system of terminology that provides better guidance for doctors on which follow-up tests to order when tests come back as abnormal. Previously, multiple classifications were used, creating widespread confusion among laboratories and treating physicians. When a Pap test comes back with an abnormal report, the results could be pre-cancerous, but they may also indicate some other benign condition.

Understanding the Causes of Cervical Cancer
With abnormal Pap results in a younger, sexually active woman, Dr. Lund says he and many other physicians have the Pap smear further tested for presence of the human papilloma virus, or HPV, because at least 98% of cervical cancers are related to that virus.

“If you have an atypical result and you don’t find the virus, then there’s generally not a problem,” Dr. Lund says. “On the other hand, if it is positive for HPV, the patient would then have a colposcopic examination of the cervix and possibly a biopsy” to more definitively diagnose whether dyplasia – or precancerous cells – are present.

Dr. Lund spoke about new findings in HPV research earlier this year at the Winter Refresher Course for Medical College of Wisconsin faculty physicians specializing in Family Practice. He also attended the recent American Society for Colposcopy and Cervical Pathology meeting at which the new Pap test recommendations were discussed.

Pap Test is Still the Gold Standard
Because of the close relationship between cervical cancer and HPV, some health organizations have suggested that the HPV test alone be the gold standard for diagnosing cervical cancer.

Dr. Lund disagrees. “So many women are exposed to HPV, if you just tested for HPV alone, it will often be positive – yet her chances of having cancer would be low. HPV is an extremely common infection, and for most women exposed to it, it eventually goes away like the common cold. In some cases, however, it can cause changes in cervical cells and have an adverse effect. Women should not ask for an HPV test unless they have an abnormal Pap.”

Another reason women should have annual pelvic examinations and Pap smears, Dr. Lund says, is that other types of cervical cancers not linked to HPV, although rare, can show up as abnormal Pap results.

Finally, he adds, medical research is dynamic, and treatment recommendations will continue to change and evolve as knowledge increases. Staying current with recent advances – and using them to promote better patient care – is just part of the job for specialists like Dr. Lund.

Barbara Abel
HealthLink Contributing Writer

This article includes information from the Froedtert & The Medical College of Wisconsin Obstetrics and Gynecology Clinic.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.