Many overprescribe the screen, telling researchers that they would recommend it to virgins (most cervical cancers arise from a sexually transmitted virus), women with inoperable cancers and even women who have had their cervix surgically removed.

Overall, the study found that only 28 percent of internal medicine doctors, 21 percent of general practitioners and 16 percent of obstetricians/gynecologists use the Pap screen in the recommended way.

"We conducted a nationally representative survey of primary care physicians in the U.S., and found that the majority of physicians do not have guideline-consistent screening recommendations," said the study's lead author, K. Robin Yabroff, an epidemiologist at the National Cancer Institute in Bethesda, Md.

However, the researchers also found that the physicians said "guidelines were influential in their practice," according to Yabroff.

The findings are published in the Nov. 3 issue of the Annals of Internal Medicine.

The Papanicolaou (Pap) test screening is used to detect early changes in cervical cells that might indicate cancer. In the past, it was recommended that sexually active women have the test every year.

But, in 2002 and 2003, the American Cancer Society (ACS), the American College of Obstetrics and Gynecology (ACOG) and the U.S. Preventive Services Task Force all changed their Pap screening recommendations, according to background information in the study. Both ACOG and the ACS recommended that when women over 30 years old had three consecutive Pap tests with normal results, those women could switch from annual tests to testing every two to three years. The task force recommended that all women be tested at least once every three years.

The ACS also recommended that a woman with three normal tests could stop screening at age 70 if she'd had no abnormal tests within 10 years. And, any woman with a life-limiting condition could stop Pap tests, according to the ACS. The task force recommended stopping screening at age 65 if past tests had been normal. ACOG felt there wasn't enough evidence to recommend a specific age to stop screening.

For the current study, Yabroff and her colleagues surveyed more than 1,200 primary care physicians, including 471 general or family practice doctors, 310 internal medicine physicians and 333 ob/gyns.

The physicians ranged in age from under 40 to over 60, and nearly two-thirds were male, according to the study. Most practiced in an urban location.

The researchers presented the physicians with questions about their screening practices, alongside four clinical vignettes describing a woman's age, along with her sexual and screening history. They then asked the doctors whether or not they would recommend screening for that woman. And, because of the differences in screening recommendations, the researchers created a composite measure to assess screening practices, according to Yabroff.

Some of the results:

• About a third (32 percent) of physicians recommended a yearly Pap test for an 18-year-old with no sexual experience.
• About 23 percent of doctors recommended an annual or biennial screen for a 66-year-old woman with advanced, inoperable lung cancer and three prior (consecutive) normal Pap results.
• More than half (54.4 percent) recommended testing between every one to three years for a 71-year-old woman with three prior normal test results.
• More than 44 percent of physicians recommended the Pap test every one to three years for a woman who had previously had her cervix removed for benign reasons.

Nearly 85 percent of the physicians surveyed described screening guidelines as "very influential." But, in practice, few actually followed the guidelines precisely. Overall, just 22 percent followed the guideline recommendations, the researchers found.

The variance in screening tended to be overuse of the test, the researchers said. The problem with overusing the test is that it may not be the best use of limited health care dollars, and more importantly could lead to additional unnecessary testing and worry for women.

Dr. Amy Chapman, an obstetrician/gynecologist at Scott and White Healthcare in Round Rock, Tex., said she was surprised by the study's findings. "In my experience, gynecologists really do follow the current recommendations from ACOG," she said.

She pointed out that those recommendations had recently changed again, which may be part of the reason physicians weren't following the guidelines consistently -- there may simply be a lag time between the changes and implementation, she said.

The bottom line, said Chapman, is that "patients should be their own advocate. Sit down with your doctor and ask what's the recommendation for you?"

More information

Learn more about cervical cancer and PAP screening from the American Cancer Society.