The recommendations fall in line with two separate sets of guidelines released earlier this year - one by the American Cancer Society and other medical groups, and another from the U.S. Preventive Services Task Force, a government-backed panel.

All of the new recommendations mark a further shift away from annual Pap testing, which was once the standard advice.

Now ACOG and the other groups say most women ages 21 to 29 should have a Pap test no more than every three years.

For women ages 30 to 65, the best option is to have a Pap test, along with a test for human papillomavirus (HPV), every five years; otherwise, a Pap test alone every three years is "acceptable."

"Women can feel very comfortable with this," said Dr. David Chelmow, referring to the longer interval between Pap tests. "The bottom line is, this is enough."

Chelmow, who heads obstetrics and gynecology at Virginia Commonwealth University in Richmond, led the development of the ACOG guidelines.

Cervical cancer is caused by long-term infection with certain types of HPV, a virus that causes warts, including genital warts. But there are over 100 strains of HPV, and only some are linked to cervical cancer. And even among women infected with those strains, only a limited number will develop cervical cancer.

The Pap test is done to look for abnormalities in cervical cells that may or may not become cancer. The HPV test helps refine things by showing whether a woman has a strain linked to cervical cancer.

But women younger than 30 should not have the HPV test, Chelmow said.

That's because women that age commonly carry the virus, but for a relatively short time before the immune system wipes it out. So testing young women would largely catch short-lived HPV infections that would not contribute to cancer later.

"HPV testing just won't work well for women in that age group," Chelmow said.

All of the new guidelines, he noted, are aimed at giving women and doctors clearer direction on how often to do cervical cancer screening.

"They're also aimed at avoiding over-testing," Chelmow said.

The downside with any cancer screening is that tests can pick up possible abnormalities where there are none. And that leads to unnecessary - sometimes invasive - follow-up tests, anxiety and healthcare costs.

Traditionally, Pap tests were done yearly. But more recently, doctors have been recommending longer intervals to avoid over-screening. The previous ACOG recommendation had been for women ages 21 to 29 to have a Pap test every two years; for women ages 30 to 65, the interval was every three years, if their last three tests had been negative.

Chelmow said these new recommendations are "much clearer."

Women younger than 21 should not be screened for cervical cancer at all, according to ACOG and the other groups.

That's because the cancer is rare at that age, while abnormalities in cervical cells are common.

But all women, Chelmow said, should keep having an annual "well woman" check-up - which includes general health checks, like having your blood pressure and cholesterol measured.

That's despite one recent review from the Cochrane Library that found regular check-ups weren't likely to be helpful for healthy people.

There is now a vaccine against HPV, and women who've gotten it may wonder if they need cervical cancer screening.

The answer is yes, Chelmow said. "They should follow the same screening recommendations as everyone else."

The two vaccines used in the U.S. guard against only two cancer-causing strains of HPV. Those two strains account for about 70 percent of all cervical cancers - which means that even vaccinated women can still develop the cancer.

The American Cancer Society estimates that about 12,200 U.S. women will be diagnosed with cervical cancer this year, and 4,200 will die from the disease.

SOURCE: bit.ly/s3TyE Obstetrics & Gynecology, November 2012.

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