Girls who get HPV vaccine before 17 can reduce cervical cancer risk by 88%: Study
Women vaccinated against human papillomavirus (HPV) have a significantly lower risk of developing cervical cancer, and the positive effect is most pronounced for women vaccinated at a young age. This is according to a large study which found that girls vaccinated before the age of 17 reduced their risk of cervical cancer by 88%. Women vaccinated between ages 17 and 30 also halved their risk of cervical cancer compared to unvaccinated women, says the research team from Karolinska Institutet, Sweden.
"This is the first time that we, on a population level, are able to show that HPV vaccination is protective not only against cellular changes that can be precursors to cervical cancer but also against actual invasive cervical cancer. It is something we have long suspected but that we are now able to show in a large national study linking HPV vaccination and development of cervical cancer at the individual level," explains the study's corresponding author Jiayao Lei, a researcher at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet.
HPV is a group of viruses that commonly cause genital warts and different types of cancer, including cervical cancer, a disease that globally kills more than 250,000 women a year. There are more than 100 varieties of human papillomavirus (HPV). Nearly all cervical cancers are caused by HPV infections, but cervical cancer may take 20 years or longer to develop after an HPV infection, according to health experts. The HPV infection and early cervical cancer typically do not cause noticeable symptoms, which is why experts recommend that it is important for women to have regular screening tests to detect any precancerous changes in the cervix that might lead to cancer. More than 100 countries have implemented national vaccination programs against HPV, reveals the study which has been published in the New England Journal of Medicine (NEJM).
Previous research has shown that the HPV vaccine protects against HPV infection, genital warts and precancerous cervical lesions that could develop into cancer of the cervix. However, there is a lack of large population-based studies that, on an individual level, have studied the link between HPV vaccine and so-called invasive cervical cancer, which is the most severe form of the disease, say researchers. Accordingly, the current analysis followed almost 1.7M women between the ages of 10 and 30 during a period of 11 years. Of those women, more than 500,000 were vaccinated against HPV, the majority before the age of 17.
The results reveal that 19 vaccinated women were diagnosed with cervical cancer compared to 538 unvaccinated women, corresponding to 47 and 94 women per 100,000, respectively, which suggests that HPV vaccine is effective against cervical cancer. "Girls vaccinated at a young age seem to be more protected, probably because they are less likely to have been exposed to HPV infection and given that HPV vaccination has no therapeutic effect against a pre-existing infection,” says study co-author Pär Sparén, also a professor at Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.
The report has been adjusted for several covariates that may influence the outcome, including age, residential area, calendar year, follow-up time, and parental characteristics such as education, income, birth country and disease history, explains the team. "In conclusion, our study shows that HPV vaccination may significantly reduce the risk of cervical cancer, especially if completed at an early age. Our data strongly supports continuing HPV vaccinations of children and adolescents through national vaccination programs," recommends Pär Sparén.