New guidelines on cervical cancer screening

By Dr. Ananya Mandal, MDMar 15 2012

Many women over the last few decades have gone in for their Pap smear tests each year. Now, two influential groups of medical experts say that having cervical cancer screening once a year is not necessary and, in fact, should be discouraged. Many women can wait as long as five years between screenings, the new guidelines say.

The new guidelines, released this Wednesday, are based on evolving knowledge acquired over the last decade about human papillomavirus, a common sexually transmitted disease that causes most cervical cancer, and the availability of an HPV test that shows whether a woman has been infected with the most common variants of the virus.

In recent years, advice on cervical cancer screening has varied widely among medical organizations, with experts recommending screening intervals ranging from one to three years and varying according to a woman's age and whether she is sexually active.

Debbie Saslow, director of breast and gynecological cancer for the American Cancer Society said the new guidelines should reassure women and their doctors that experts have neared a consensus on what has been a controversial issue in prevention medicine. “I think everyone is on the same page for the first time that I can remember,” Saslow said.

By having both a Pap smear and an HPV test - known as co-testing - women ages 30 to 65 can safely go five years between screenings if the results are negative, said Dr. Michael LeFevre, co-vice chair of the U.S. Preventive Services Task Force, which published the other set of guidelines in the Annals of Internal Medicine.

This is the first time that co-testing has been formally recommended as an alternative to Pap smears alone, although some doctors have been offering the tests in tandem for some time. Studies show that the death rate for cervical cancer is not affected by lengthening screening intervals, LeFevre said, and the move would reduce the number of false-positive tests and unnecessary follow-up procedures. “You can have fewer Pap smears and it is still as safe and effective,” he said. “That is the product of science and what we've learned about HPV.”

“HPV infection is usually self-limited,” LeFevre said. “Within a couple of years most women will clear it on their own with no problem.” But since the presence of the virus in women 30 and older may signal a persistent infection that could increase cancer risk, co-testing is of value in women 30 to 65, both documents said.

Both the U.S. Preventive Services Task Force and the consortium of medical groups led by the American Cancer Society continue to emphasize that Pap tests are important, however. More than 11,000 new cases of cervical cancer are diagnosed each year in the U.S. and about 4,000 women die from the disease, largely because they didn't get screened and their cancers were caught too late. “If you look at cervical cancer today in the U.S., at least half of the women who get it have not been screened,” LeFevre said. “Extending out the interval to three years or five years doesn't mean, 'Gee, this must not be important.'”

Until now, use of the HPV test in combination with the Pap smear was not endorsed by the U.S. Preventive Services Task Force, but it changed its position following recent reports that demonstrated the value of using both tests. One such report, a large study published in December in the journal Lancet Oncology, showed that women who got an HPV test and a Pap smear had fewer cases of pre-cancers and cancers five years later compared with women who got only a Pap smear.

The American Cancer Society-led guidelines go slightly further, stating that co-testing is the “preferred” screening strategy for women 30 to 65. Other authors of the document included the American Society for Colposcopy and Cervical Pathology and the American Society for Clinical Pathology; in addition, it was endorsed by the American College of Obstetricians and Gynecologists.
Both documents recommend several other changes to screening.

• Young women don't need Pap smears until age 21.
• Women ages 21 to 29 should be screened with the Pap smear alone every three years.
• Women can now stop having Pap smears and HPV tests at age 65. Previous guidelines called for halting screening at age 70.