Most women can wait three to five years between Pap tests to screen for cervical cancer, according to guidelines released by the American College of Obstetricians and Gynecologists (ACOG).
The latest recommendation, which appeared in Obstetrics and Gynecology and is in line with earlier sets of recommendations, marks a further shift away from annual Pap testing, which was once the standard advice.
Now ACOG and the other groups say most women aged 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 David Chelmow, who heads obstetrics and gynecology at Virginia Commonwealth University and led the development of the ACOG guidelines. "The bottom line is, this is enough."
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, only some linked to 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, Cherlmow 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.
All the new guidelines, Chelmow noted, are aimed at giving women and doctors clearer direction on how often to do cervical cancer screening - and avoid over-testing.
There is now a vaccine against HPV, and women who have 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 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.
By Rachael Rettner
The human papillomavirus vaccine provides a benefit to women even if they are not vaccinated, via a phenomenon known as herd immunity, a new study suggests.
Among the women in the study, there was a decrease in the percentage who were infected with the four HPV strains included in the vaccine (HPV 6, 11, 16, and 18) in the years after the vaccine was introduced, compared with earlier years.
This decrease in HPV prevalence was seen among both vaccinated and unvaccinated women, the researchers said.
The findings show that even with relatively low rates of women getting vaccinated, the vaccine produces some degree of herd immunity — protection of unvaccinated people that occurs because a critical portion of the population has been innoculated.
However, while the findings are encouraging, "This is not reason not to get vaccinated," said study researcher Dr. Jessica Kahn, a physician of adolescent medicine at Cincinnati Children's Hospital. Kahn noted that one in four unvaccinated participants in the study were infected with a high-risk strain of HPV. A woman can also protect her partner by getting vaccinated, Kahn said.
Because the study was conducted in just one community of mainly African American women, further research is needed to confirm the results and see if the findings apply to the population as a whole.
The first HPV vaccine, called Gardasil and manufactured by Merck, was licensed for use in the United States in June 2006.
To study the effect of the vaccine, Kahn and colleagues analyzed information from two groups of sexually active women ages 13 to 26. One group consisted of 368 women who were not vaccinated, and who visited clinics in Cincinnati between 2006 and 2007. The second group consisted of 409 women who visited the clinics between 2009 and 2010, about 60 percent of whom had received at least one of the three shots in the HPV-vaccination series.
Overall, the percentage of women infected with one of the HPV strains included in the vaccine decreased from 31 percent in the group that visited the clinics between 2006 and 2007, to 13.4 percent in the group that visited in 2009 and 2010 — a 58 percent decrease.
Among women in the latter group, 9.9 percent of those who were vaccinated tested positive for HPV, while 15.4 percent of the unvaccinated women were infected.
The percentage of women infected with HPV strains not included in the vaccine increased after the vaccine's introduction, from about 60 percent to 75 percent, but the researchers said this finding should be interpreted with caution, because there is no biological reason this would happen so quickly.
The study is "good news that comes surprisingly soon," said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University. Schaffner said he would have expected a larger portion of the population needed to be vaccinated, including boys, to see herd immunity.
"It's impressive if other studies can confirm it," Schaffner said.
The study is a reminder that "vaccination is not just about the individuals getting vaccinated…it's about everyone else in the community," Schaffner said.
Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia, said he would expect to see herd immunity against the strains in the vaccine starting at a vaccination rate of 40 percent, which is the national average.
The vaccine's effectiveness in reducing HPV prevalence is expected to translate into a decrease in cervical cancer in the community, Kahn said. (HPV is known to cause most cases of cervical cancer ).
Because of the high prevalence of HPV strains, the findings underscore the importance of vaccinating children before they become sexually active, when they are 11 or 12 years old. And the study shows that older women, who are recommended for "catch up" vaccination, also derive a benefit, Kahn said.
The study is published in the July 9 issue of the journal Pediatrics.
More from Vitals:
Most women can go as long as five years between cervical cancer screenings as long as they make sure to get both a Pap smear and an HPV test when they do get examined, a government panel said Wednesday.
The interval between cervical cancer screenings can safely be extended for women between the ages of 30 and 65, according to the new recommendations from the U.S. Preventive Services Task Force.
Women ages 21 to 30 should still get a Pap smear every three years, the interval currently recommended. But those younger than 21 and older than 65 can skip the screen altogether, the experts concluded.
The panel is urging a extended intervals in screenings in an attempt to cut back on the number of women who end up being treated for lesions that might resolve on their own.
The downside could be a very small potential increase in the number of women who might die of cervical cancer, experts said.
“It’s a trade-off,” said Dr. Michael LeFevre, co-vice chair of the task force and a professor of family and community medicine at the University of Missouri at Columbia.
While screening more often might turn up more cancers and pre-cancerous lesions, it would also lead to far more unpleasant and painful therapies for women who might ultimately not have needed them, LeFevre said.
When a lesion is found, generally a colposcopy is ordered, said Dr. Alan Waxman, a professor of obstetrics and gynecology at the University of New Mexico.
And the often painful test can amount to a lot of unnecessary suffering given that many lesions frequently disappear on their own. For women who’ve never experienced a colposcopy, Waxman offered this description: “It’s like a Pap test on steroids.”
Beyond this, lesions may end up being excised in an uncomfortable procedure that can impact future fertility, the task force found. Studies have shown that some treatments for precancerous lesions can result in adverse pregnancy outcomes, including pre-term delivery, an infant that is underweight at birth, or even stillbirth or death shortly after delivery.
Until experts can find a way to cut back on colposcopies and excisions for precancerous lesions, it makes sense to screen less often because this will give some lesions time to resolve on their own, Waxman said.
He predicted that the new recommendations will take time to be accepted into practice.
“I anticipate there will be some apprehension among ob-gyns about it,” Waxman said. “It’s something new. And there’s always a concern if you screen less often you’re going to miss disease.”
Dr. Thomas Randall is one of those who isn’t yet convinced that the proposed changes are the best solution.
One thing missing from the new recommendations are studies that look at how women feel about treatment issues, said Randall, director of gynecologic oncology at Pennsylvania Hospital.
“I applaud the panel’s effort to minimize the emotional and physical burden of treatment on patients,” Randall said. “But I think we need to think very carefully about what patients’ preferences actually are.”
Beyond this, Randall said, it might make more sense to look at ways to decrease the number of colposcopies and excisions rather than cutting back on screening.
“Limiting screening seems a little paternalistic,” he explained. “Maybe we should be looking more at treatment patterns than at screening patterns in order to decrease the burden of treatment.”
The new recommendations were published in the Annals of Internal Medicine.