Days after a government advisory panel rolled back its recommendations on mammography screening for breast cancer, another influential group issued revised guidelines on the use of Pap smears to detect cervical cancer, recommending that young women delay getting their first test.
In its new guidelines issued Friday, the American College of Obstetricians and Gynecologists (ACOG) recommended that adolescent girls wait until age 21 to get their first Pap smear. The College also recommended less frequent screening for older women: every two years for women in their 20s instead of yearly, and every three years for women 30 and older. Previously, the ACOG along with other national groups, including the American Cancer Society and the U.S. Preventive Services Task Force (or USPSTF, the same group that revised its mammography screening advice) had advised girls to begin yearly Pap tests within three years of their first sexual encounter or, regardless of their sexual activity, by the time they reach 21.
Citing a drop in cervical cancer rates, the ACOG is now loosening its guidelines. The group also took into account recent studies on the risks of screening. Risks include the removal of abnormal lesions found during Pap smears, which are common in young women and teens, but often go away on their own if left untreated. The procedures used to remove the lesions may be linked to long-term reproductive harms, such as premature birth, underweight babies and an increased risk of cesarean section birth. Weighing the risks, the ACOG determined that the evidence supported later, and less frequent screening. "A review of the evidence to date shows that screening at less frequent intervals prevents cervical cancer just as well, has decreased costs, and avoids unnecessary interventions that could be harmful," Dr. Alan Waxman, a physician at the University of New Mexico and head of ACOG's Committee on Practice BulletinsGynecology, said in a statement.
Since the 1970s, when Pap testing became a part of routine gynecological exams, the rate of cervical cancer in the U.S. has fallen more than 50% in 1975 there were 14.8 cases per 100,000 women, and by 2006, only 6.5 per 100,000 women. But the cancer, which is primarily caused by infection with the sexually transmitted human papillomavirus (HPV), is rare among teens under 20. Only about 14 cases are reported each year in the U.S. in teenagers, compared with 123 cases among women ages 20 to 24, according to the Centers for Disease Control and Prevention. The numbers were low enough in young women to prompt the ACOG to push back its screening guidelines. Overall, there are 4,070 cervical-cancer deaths and 11,270 new cases each year in the United States.
The guidelines advise women between the ages of 21 and 30 to be screened once every two years for cervical cancer. In women over 30, the guidelines allow for three years between screenings, if patients have three consecutive normal Pap smears and no prior history of abnormalities. Between 65 and 70, women may stop have Pap smears altogether, if they have had three normal tests in a row and negative results over the last 10 years. However, women with HIV, previously abnormal Pap tests, or other problems that would suppress the immune system or increase the risk of aggressive cervical cancer may need more frequent screening.
Cervical cancer is slow growing giving doctors time to find it and studies show that among women in their 20s, the risk of developing cervical cancer does not increase by reducing the frequency of Pap tests to every two years. Although the HPV infection rate is high among sexually active teens and young adults, the virus is typically cleared by the woman's immune system within a year or two of infection. Few cases of HPV infection lead to cancer; when they do, the cancer may develop up to 10 to 20 years after exposure to the virus.
The change in Pap testing does not represent as monumental a shift as the USPSTF's new advice on mammography, since Pap testing of adolescents, while recommended, has not become as entrenched as mammography as a preventive tool. Still, both new sets of cancer screening guidelines exemplify an effort by leading medical organizations to base their advice on scientific data, rather than an assumption that more screening always leads to better prevention. "Physicians have a hard time letting go of screening tests that make them feel comfortable," says Dr. Karen Soren, director of adolescent medicine at New York Presbyterian Morgan Stanley Children's Hospital. "The larger view is that screening is always good. But it's also good to reassess and take another look every once in a while."