Women who have been vaccinated against human papillomavirus (HPV) may be able to start cervical cancer screening later in life and receive less frequent screenings, with an interval of five to 10 years instead of the recommended three years.
The study, “Optimal Cervical Cancer Screening in Women Vaccinated Against Human Papillomavirus,” published in the Journal of the National Cancer Institute, supports a reassessment of cervical cancer screening policies in women who have been vaccinated against HPV.
In 2012, cervical cancer screening guidelines were established across major guideline-making organizations, recommending that all women in the U.S. receive screening for cervical cancer with a Pap test (which detects abnormal cells in the cervix) every three years starting at age 21. Women had the option to switch to a combination of a Pap test and an HPV test every five years beginning at age 30.
With the availability of HPV vaccines and recommendations for routine vaccinations of young girls since 2017, it is expected that cervical cancer will decrease. But current guidelines do not differentiate women according to their vaccination status.
“This analysis enabled us to examine what would happen if we shifted from the current way we screen for cervical cancer —essentially, recommending the same type of screening for all women— to screening that takes into account whether women have been vaccinated against HPV and therefore face a substantially lower risk of cervical cancer,” Jane Kim, professor of health decision science at Harvard T.H. Chan School of Public Health, said in a press release. “We found that continuing intensive screening among HPV-vaccinated women yields excessive costs and harms with little to no health benefit.”
To estimate the risks and benefits of different screening protocols according to women’s vaccination status, researchers at the Harvard Chan School developed a disease simulation model, projecting the health and economic effects of changing screening strategies in women vaccinated with one of the three different types of HPV vaccines.
The bivalent and quadrivalent vaccines (HPV-2 and HPV-4) target two HPV types that cause nearly 70 percent of all cervical cancer cases, while the nonavalent vaccine targets nine HPV types, seven of which are carcinogenic and cause 90 percent of cervical cancer cases. The researchers’ goal was to assess which screening strategies would provide the biggest health benefit in the most cost-effective way.
Results showed that women vaccinated with the nonavalent vaccine, which had the lowest risk for cervical cancer, only require screening every 10 years starting at age 30 or 35, requiring a total of four screenings in their lifetime. On the other hand, women vaccinated with the bivalent or quadrivalent vaccines, which are earlier versions of the nonavalent vaccine, would require screening starting at age 25 or 30 and then every five years.
The study also revealed that these women may only be screened with an HPV test alone, as it provided similar health benefits as a Pap test or a combination of Pap/HPV testing. The HPV test, the researchers found, is highly sensitive and can identify women who are likely to develop cervical cancer more efficiently than the other methods.
The researchers note, however, that their study is based on women who were fully vaccinated in pre-adolescence and followed recommended screening protocols, which may be a study limitation considering that a large percentage of women did not receive all three doses of the vaccines or were fully compliant in screening guidelines.
As the data for the actual vaccination uptake rates and screening compliance become available, future studies should take this information into account to draw conclusions based on real life behaviors.