Scimex: The introduction of the human papillomavirus (HPV) vaccine in the US led to a decrease in the rate of high-grade cervical lesions - abnormal tissue changes that can lead to cancer - in young women, say US scientists. However, the benefits in terms of reduced incidence of cancers themselves will take many years to evaluate because of the long lag time between infection with HPV and the development of cancer, they say.
Study Finds Decreased Rates of High-Grade Cervical Lesions in
Young Women after Approval of HPV Vaccines and Changes in Cancer
A new analysis indicates that rates of high-grade cervical lesions
decreased in young US women after vaccines were made available to
protect against human papillomavirus (HPV), but the trend may be due in
part to changes in cervical cancer screening recommendations. Published
early online in CANCER,
a peer-reviewed journal of the American Cancer Society, the study
illustrates some of the challenges in monitoring a vaccine’s impact
during a time of concurrent changes in screening.
More than half of high-grade cervical lesions, which are abnormal
tissue changes that can lead to cancer, are caused by persistent HPV
infection that can be prevented if a person receives an HPV vaccine.
Monitoring trends in the incidence of these lesions is helpful for
evaluating the impact of HPV vaccination.
A team led by Susan Hariri, PhD, of the US Centers for Disease
Control and Prevention, found that in the first few years after HPV
vaccination was introduced in the United States (2008-2012), there were
large and uniform declines in high-grade cervical lesions in young women
across the country who were aged 18 to 20 years, and to a lesser
extent, in women aged 21 to 24 years.
Dr. Hariri noted that high-grade cervical lesions are asymptomatic
and can only be detected through routine cervical cancer screening.
Because screening recommendations were changing during the time period
of this study, the investigators also looked at trends in cervical
cancer screening utilization. “In particular, screening is no longer
recommended in women before age 21 years, and we found substantial
declines in screening in 18 to 20 year olds that were consistent with
the new recommendations,” said Dr. Hariri. While screening also declined
in 21 to 24 year old women, the decreases in screening were much
smaller. “We think that the decreases in high-grade lesions in this
group reflect changes in screening but also may be partially due to HPV
vaccination.” Dr. Hariri added that the greatest benefit of HPV
vaccination—reducing the burden of cervical cancer and other
HPV-associated cancers—will take many years to evaluate because of the
long lag time between infection with HPV and the development of cancer.
In an accompanying editorial, Harinder Brar, MD and Allan Covens, MD,
of the University of Toronto, stated that the study is significant
because it is the first to look at the incidence trends of high-grade
cervical lesions in the post-vaccination era. “The study highlights that
while preliminary data demonstrates a drop in… incidence rates, the
results may be confounded by the changes in cervical screening