Cervical cancer and CIN3 rates are significantly
reduced by the bivalent HPV vaccine.
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| Image: Human Papillomavirus | InStyleHealth |
According to an observational study from England, the
risk of cervical cancer and grade 3 cervical intraepithelial neoplasia (CIN3)
was significantly reduced among girls who were given the bivalent human
papillomavirus (HPV) vaccine, particularly those who were given it around the
age of 12–13 years.
"We discovered a significant reduction in cervical
cancer rates in all three vaccinated cohorts, particularly in those who were
provided the vaccination in school year 8 (aged 12–13 years)," the authors
noted.
"As expected, vaccination against HPV was most
successful in the cohorts immunized at ages 12–13, among whom the uptake was
largest and prior infection was least likely," stated study co-author Dr
Kate Soldan of Public Health England's National Infection Service in London,
UK.
"This study shows a considerable reduction in
cervical cancer rates in vaccinated cohorts, providing the first direct
evidence of the impact of the UK HPV vaccination campaign on cervical cancer
incidence," Soldan explained.
In September 2008, HPV immunization with a bivalent
vaccine became a regular vaccination for females aged 12–13 years in England.
In 2008–2010, a catch-up program for females aged 14–18 years was also
implemented.
Female residents aged 20–64 years who were diagnosed
with cervical cancer or CIN3 between January 2006 and June 2019 were identified
using data from a population-based cancer registry. During the 13.7
million-years of follow-up, a total of 27,946 instances of cervical cancer and
318,058 cases of CIN3 were diagnosed in women aged 20 to 30 years.
Girls between the ages of 16 and 18 who were provided
the HPV vaccine had a 34% lower risk of cervical cancer than uninfected women.
[Lancet 2021;398:2084-2092] [Lancet 2021;398:2084-2092]
This relative risk decrease was considerably greater
among girls aged 14–16 and 12–13 years, with a 62 percent and 87 percent
reduction in risk, respectively. 89 percent of those in the latter group had
received at least one dose of the HPV vaccine, and 85 percent had received all
three doses.
Similarly, as compared to uninfected women, those who
were provided the HPV vaccine at the ages of 16–18, 14–16, and 12–13 years saw
a 39 percent, 75 percent, and 97 percent reduction in the risk of CIN3,
respectively.
By June 2019, it was anticipated that there were 448
fewer than expected incidences of cervical cancer and 17,235 fewer than
expected cases of CIN3 among vaccinated cohorts in England.
"This [research] is a significant step forward in
the prevention of cervical cancer." "We hope that these new findings
boost vaccination uptake because the success of the immunization campaign is
determined not only by the vaccine's efficiency but also by the proportion of
the population that has been vaccinated," Soldan added.
The authors noted that the HPV vaccine offer in this
study only pertains to age groups and does not take into account unobserved
characteristics like behavior and lifestyle. Furthermore, there were no data on
individual-level efficacy or HPV types for each cancer case. They also
mentioned that the incidence of cervical cancer in young women, such as the cohort
analyzed here, is low.
"Cervical cancer incidence fluctuates fast with
age and is influenced by screen-detected malignancies, particularly on the
initial screen," they said. "Over time, the precise age of initial
screening and screening uptake fluctuates. Even little changes to cervical
screening (or the reporting of cervical histology) or cancer registration could
have a big impact on CIN3 trends in women in their 20s."
Professors Maggie Cruickshank of the University of
Aberdeen, Aberdeen, UK, and Mihaela Grigore of the University of Medicine and
Pharmacy "Grigore T Popa" Lasi, Lasi, Romania, wrote in a commentary,
"The relative reductions in cervical cancer expected as a result of the
HPV vaccination program support the anticipated vaccine effectiveness."
[Lancet 2021;398:2053-2055] [Lancet 2021;398:2053-2055]
"The magnitude of the HPV vaccination effect
reported in this study should also encourage vaccination programs in low- and
middle-income countries, where the problem of cervical cancer is a far greater
public health issue than in countries with well-established vaccination and
screening systems," researchers stated.
"Aside from vaccine availability, the most
critical issue... is educating the community to accept vaccination because a
high rate of immunization is a key part of success," they noted.