WEDNESDAY, Oct. 15, 2003 (HealthDayNews) -- New evidence supports existing recommendations that Pap smears be performed only once every three years for women who are at a low risk for cervical cancer.
For women over the age of 30 who have already had negative annual Pap tests at least three years in a row, extending the interval between tests increases the risk of cervical cancer only by about three in 100,000 women.
That is roughly equivalent to the annual incidence of breast cancer in men aged 45 to 64, say the authors of the study, which appears in the Oct. 16 issue of the New England Journal of Medicine.
The Papanicolaou test, which detects abnormalities in cells before they actually become cancer, is the most widely used cancer-screening test in the United States. More than 80 percent of women get the test in any two-year period and more than 90 percent have been screened at least once. Since the test was adopted in the 1960s, mortality from cervical cancer has plummeted.
Guidelines from the American Cancer Society and the American College of Obstetrics and Gynecology recommend that low-risk women -- those over the age of 30 with previous negative tests -- get Pap smears less often than annually. Many doctors still offer tests more frequently, however.
Why? "Reasons are myriad, including the lack of information on risk," says study author Dr. George F. Sawaya, an associate professor of obstetrics, gynecology and reproductive sciences at the University of California at San Francisco. The information in the current study, he adds, can be used by physicians and patients to make decisions about how often to screen.
Sawaya and his colleagues looked at about 1.2 million records from the National Breast and Cervical Cancer Early Detection Program, which is administered by the U.S. Centers for Disease Control and Prevention and has provided screening to low-income, under-insured, or uninsured women in the United States since 1991.
The researchers noted the number of positive Pap smears and then calculated the estimated cancer risk.
The estimated extra risk of cancer for women aged 30 to 44 who have had three consecutive negative tests was two in 100,000 women, for women aged 45 to 59 it was one in 100,000, and for women 60 to 64 years it was one in 100,000. The overall cancer risk in each group would then be five in 100,000, two in 100,000, and one in 100,000 respectively. Having annual Pap smears produced no difference in the oldest age group.
The prevalence of cancer decreased as the number of previous negative tests accumulated.
Although the risk per woman is small, the overall numbers are larger. "Five per 100,000 cancers missed with tri-annual screening is small, but when you look at the population, that's 500 extra cancers. That's not so small," says Dr. Giuseppe Del Priore, an associate clinical professor of gynecologic oncology at New York University School in New York City.
There are also other advantages to going in for an annual Pap smear, Del Priore says. "To consider a Pap smear a 30-second technical intervention that takes place in some kind of automated void is mistaken," he says. "When a woman who goes to a doctor says everything's fine, she doesn't mean just the Pap smear's fine. She means the blood pressure, weight, tobacco, vaccination."
Still, Sawaya and others believe the frequency of screening can be reduced for many, but not all, women. "The information [in the current study] only applies to women over the age of 30 who have had three annual negative Pap smears," says Dr. Sarah Feldman, author of an accompanying editorial and director of the Pap smear evaluation center at Brigham and Women's Hospital in Boston. "It does not apply to the general population."
"Individual women should first and foremost speak with their clinicians to see if they are indeed good candidates for less screening if they desire to be screened less often than annually," Sawaya says.
More information
To see Pap smear guidelines, visit the American College of Obstetrics and Gynecology and the American Cancer Society. For more on the National Breast and Cervical Cancer Early Detection Program, visit the U.S. Centers for Disease Control and Prevention.
