Pap smears in women under 21 do more harm than good, new guidelines from the American College of Obstetricians and Gynecologists (ACOG) say.
In most cases such tests reveal only human papillomavirus (HPV) infections, which rarely lead to cervical cancer in women under 21, said Dr. Mark Einstein of the Albert Einstein College of Medicine (no relation) in the Bronx, New York.
"They have a better chance of winning the lottery than getting cancer at that age," said Einstein, who is an ACOG fellow but did not work on the guidelines.
Doctors usually go on to do a small biopsy of the cervix if a Pap smear shows abnormal results; they also monitor the young women more closely.
"Over-screening adolescents is really detrimental to young women," Einstein told Reuters Health. "We increase their anxiety, we increase their time away from school and work."
The new guidelines, published in the journal Obstetrics & Gynecology, reinforce earlier recommendations issued in November 2009. But they add that adolescents with compromised immune systems — due to HIV infections, organ transplants or long-term steroid use, for instance — should not wait until 21 to be screened.
Although this group makes up less than one percent of adolescents, said Einstein, their weak immune systems may allow HPV to develop into cancer much more easily than in healthy individuals.
Prior recommendations called for annual cervical cancer screening to start three years after a woman first becomes sexually active, or by age 21.
HPV is the most common sexually transmitted disease in the world. About 20 million Americans currently are infected with HPV, according to the Centers for Disease Control and Prevention.
In the past 30 years, cervical cancer rates in the United States have fallen by more than half, due in large part to widespread use of cervical cancer screening.
In its November 2009 guidelines, ACOG recommended that women between 21 and 30 years should undergo cervical cancer screening once every two years instead of an annual exam. Those 30 and older can be screened once every three years. The new recommendations do not refer to women between 21 and 30.