From the Journals

HPV vaccines reduce cervical cancer rates in young females


 

Two different studies have found that, provided young females are immunized with the human papilloma virus (HPV) vaccine at a young enough age, both the incidence of and mortality from cervical cancer can be dramatically curtailed, data from the United Kingdom and to a lesser extent, the United States indicate.

In the U.K. study, published online in The Lancet, researchers showed that the national vaccination program against HPV, initiated in England in 2008, has all but eradicated cervical cancer and cervical intraepithelial neoplasia (CIN3) in young girls who received the vaccine at the age of 12 and 13 years (school year 8) prior to their sexual debut.

In this age group, cervical cancer rates were 87% lower than rates among previously nonvaccinated generations, while CIN3 rates were reduced by 97%, as researchers report. “It’s been incredible to see the impact of HPV vaccination, and now we can prove it prevented hundreds of women from developing cancer in England,” senior author Peter Sasieni, MD, King’s College London, said in a statement. “To see the real-life impact of the vaccine has been truly rewarding,” he added.

“This study provides the first direct evidence of the impact of the UK HPV vaccination campaign on cervical cancer incidence, showing a large reduction in cervical cancer rates in vaccinated cohorts,” Kate Soldan, MD, UK Health Security Agency, London, said in the same statement.

“This represents an important step forward in cervical cancer prevention, and we hope that these new results encourage uptake as the success of the vaccination programme relies not only on the efficacy of the vaccine but also the proportion of the population vaccinated,” she added.

Vanessa Saliba, MD, a consultant epidemiologist for the UK Health Security Agency, agreed, adding that “these remarkable findings confirm that the HPV vaccine saves lives by dramatically reducing cervical cancer rates among women.”

“This reminds us that vaccines are one of the most important tools we have to help us live longer, healthier lives,” she reemphasized.

British HPV program

When initiated in 2008, the national HPV vaccination program used the bivalent, Cervarix vaccine against HPV 16 and 18. As researchers noted, these two HPV types are responsible for 70%-80% of all cervical cancers in England.

However, in 2012, the program switched to the quadrivalent HPV vaccine (Gardasil) which is also effective against two additional HPV types, 6 and 11, both of which cause genital warts. The program also originally recommended the three-dose regimen for both HPV vaccines.

Now, only two doses of the vaccine are given to girls under the age of 15 even though it has been shown that a single dose of the HPV vaccine provides good protection against persistent infection, with efficacy rates that are similar to that of three doses, as the authors point out.

Among the cohort eligible for vaccination at 12 or 13 years of age, 89% received at least one dose of the HPV vaccine while 85% of the same age group received all three shots.

Cancer registry

Data from a population-based cancer registry was used to estimate the early effect of the bivalent HPV program on the incidence of cervical cancer and CIN3 in England between January 2006 and June 2019. During the study interval, there were 27,946 diagnoses of cervical cancer and 318,058 diagnoses of CIN3, lead author Milena Falcaro, MD, King’s College London, and colleagues report. Participants were then analyzed separately according to their age at the time of vaccination and the incidence rates calculated for both cervical cancer and CIN3 in the three separate groups.

For slightly older girls who received the vaccine between 14 and 16 years of age (school year 10-11), cervical cancer was reduced by 62% while CIN3 rates were reduced by 75%. For those who received the vaccine between 16 and 18 years of age (school year 12-13), cervical cancer rates were reduced by 34% while CIN3 rates were reduced by 39%, study authors add.

Indeed, the authors estimate that by June 2019 there were approximately 450 fewer cases of cervical cancer and 17,200 fewer cases of CIN3 than would otherwise have been expected in the vaccinated population in England.

The authors acknowledge that cervical cancer is rare in young women and vaccinated populations are still young. For example, the youngest recipients would have been immunized at the age of 12 in 2008 and would still be only 23 years old in 2019 when the study ended.

Thus, the authors emphasize that, because the vaccinated populations are still young, it’s too early to assess the full effect of HPV vaccination on cervical cancer rates.

Asked to comment on the study, Maurice Markman, MD, president, Medicine and Science Cancer Treatment Centers of America, pointed out that results from the British study are very similar to those from a Swedish study assessing the effect of the quadrivalent vaccine alone.

“You can put any superlatives you want in here, but these are stunningly positive results,” Dr. Markman said in an interview. As an oncologist who has been treating cervical cancer for 40 years – particularly advanced cervical cancer – “I can tell you this is one of the most devastating diseases to women, and the ability to eliminate this cancer with something as simple as a vaccine is the goal of cancer therapy, and it’s been remarkably successful,” he stressed.

Editorial commentary

Commenting on the findings, editorialists Maggie Cruickshank, MD, University of Aberdeen (Scotland), and Mihaela Grigore, MD, University of Medicine and Pharmacy, Lasi, Romania, point out that published reports evaluating the effect of HPV vaccination on cervical cancer rates have been scarce until now.

“The most important issue, besides the availability of the vaccine ... is the education of the population to accept vaccination because a high rate of immunization is a key element of success,” they emphasize. “Even in a wealthy country such as England with free access to HPV immunization, uptake has not reached the 90% vaccination target of girls aged 15 years set by the WHO [World Health Organization],” the editorialists add.

Dr. Cruickshank and Dr. Grigore also suggest that the effect HPV vaccination is having on cervical cancer rates as shown in this study should also stimulate vaccination programs in low- and middle-income countries where cervical cancer is a far greater public health issue than it is in countries with established systems of vaccination and screening.

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