Jane J. Kim, PhD
A new study by researchers at the Harvard T.H. Chan School of Public Health has found that women who received the HPV vaccine series as adolescents may have less intensive cervical cancer screening, including starting Pap tests at a later age and extending the time between them.
“The current guidelines, which don’t differentiate based on vaccine status, really don’t make sense for women who have been vaccinated,” said study investigator Jane J. Kim, PhD, professor of Health Decision Science, Department of Health Policy and Management and Center for Health Decision Science, at the Harvard T.H. Chan School of Public Health. “It is overkill in these women. Hopefully, these guidelines will be revisited to look at the heterogeneity and changes in risk that have been introduced by vaccination.”
The study evaluated women who received the HPV-vaccine at the recommended age of 11 or 12 years old and are now in their early 20s, which is the recommended cervical screening age. The quadrivalent/4vHPV vaccine (Gardasil) was approved for women aged 11 to 26 in 2006, followed by the bivalent/2vHPV (Cervarix) vaccine for the same age group of women in 2009. Both vaccines target 2 of the cancer-causing HPV viruses that contribute to 70% of cervical cancers. The newer 9-valent/9vHPV vaccine (Gardasil 9), approved in 2014, targets 7 types of HPV that contribute to 90% of cervical cancers.
Current cervical cancer screening guidelines recommend all women receive a cytology or Pap test every 3 years starting at age 21, with the option of switching to Pap/HPV co-testing every 5 years beginning at age 30.
“We are talking about a pretty dramatic reduction in baseline risk if women have been vaccinated by either of these baseline vaccines,” said Kim. “We wanted to look at if, based on this, we should be continuing with what is recommended for average-risk women in these vaccinated women.”
Researchers found that for women who received the recommended dose of the quadrivalent or bivalent HPV vaccine, screening can be initiated later (age 25 to 30), and frequency of screening can be extended to every 5 years.
Women who were vaccinated with the 9-valent vaccine require screening even less frequently, beginning at age 30 to 35 with a frequency of once every 10 years.
Screening should also shift from Pap test screening, to primary HPV testing, said Kim. In 2015, the Society of Gynecologic Oncology and the American Society for Colposcopy and Cervical Pathology issued joint guidance stating that the HPV test alone for cervical cancer screening is an effective alternative to the current recommendation for screening with the Pap test alone or co-testing with Pap and HPV testing.
“We can move away from Pap testing all together, and actually move to primary HPV testing—to only test for the high-risk type that cause cancer,” said Kim.
There are several benefits to less intensive cervical cancer screening. A Pap test can lack sensitivity and specificity, leading to overtreatment and unnecessary cost. Overtreatment of precancerous lesions identified by a Pap test has been linked to adverse pregnancy outcomes for women of reproductive age, including preterm birth, according to Kim.
“The more that you test, you are inviting some unnecessary procedures and what some might consider harms,” said Kim. “To be able to moderate the screening schedule to basically generate the same amount of benefits that we are observing, if not more, and at a reduced rate of harm, including unnecessary diagnostic procedures and unnecessary costs, is a win–win.”
Several questions remain unanswered regarding the impact that HPV vaccines have had on risk and what the optimal screening method for women who have been vaccinated should be going forward. This will continue to evolve as more women receive the vaccine.
Investigators at Harvard T.H. Chan School of Public Health plan to continue investigation of this topic, said Kim.
“I am definitely interested to see how this plays out in clinical practice in the United States,” she said. “We will be continuing to study this area.”