I do repeat myself repeatedly, I admit, especially about cancer. There are really only a handful of ways to lower your risk of cancer – stop smoking, stay out of the sun, eat a “healthy” diet, keep a healthy weight, don’t drink alcohol, and a few other things. One of those few science-based methods to stave off cancer is getting vaccinated against cancer-causing viruses. The HPV vaccine and hepatitis B vaccine (see Note 1) are some of the most powerful tools in cancer prevention.
The Centers for Disease Control and Prevention (CDC) have published a detailed report of HPV-related cancers in the USA, and it states that there are over 41,000 HPV-related cancers diagnosed every year. The National Cancer Institute categorizes “common cancers” as those with over 40,000 new cases a year – if we could lump all of these HPV-related cancers into one group, it would be considered a common cancer, contradicting the anti-vaccine memes that HPV isn’t that dangerous.
And the HPV vaccine could prevent most of those cancers by blocking the HPV types that cause those cancers.
All about HPV vaccines
Genital and oral human papillomavirus (HPV) infections are the most common sexually transmitted infections (STI) in the USA. HPV is generally transmitted from personal contact during vaginal, anal or oral sex.
It’s important to note that there are more than 150 strains or subtypes of HPV that can infect humans – however, only 40 of these strains are linked to one or more different cancers. Of those 40 strain, most are fairly rare.
Although the early symptoms of HPV infections aren’t serious and many HPV infections resolve themselves without long-term harm, HPV infections are causally linked to many types of cancers in men and women. According to current medical research, here are some of the cancers that are linked to HPV:
In addition, there is some evidence that HPV infections are causally linked to skin and prostate cancers. The link to skin cancer is still preliminary, but there is much stronger evidence that HPV is linked to many prostate cancers.
HPV is believed to cause nearly 5% of all new cancers across the world, making it almost as dangerous as tobacco in that respect. According to the CDC, roughly 79 million Americans are infected with HPV – approximately 14 million Americans contract a new HPV every year. Most individuals don’t even know they have the infection until the onset of cancer. The CDC also states that over 41,000 HPV-related cancers are diagnosed in the USA every year.
There were two HPV vaccines on the world market before 2014. GSK, also known as GlaxoSmithKline, produced Cervarix, a bivalent (protects against two HPV strains) vaccine. It has been withdrawn from the US market (although available in many other markets), because of the competition from the quadrivalent (immunizes against four different HPV strains) and 9-valent (against nine HPV strains) Gardasil vaccines.
Merck manufactures Gardasil, probably the most popular HPV vaccine in the world. The first version of the vaccine, quadrivalent Gardasil, targets the two HPV genotypes known to cause about 70% of cervical cancer and two other HPV genotypes that cause genital warts. In Europe and other markets, Gardasil is known as Silgard.
The newer Gardasil 9, approved by the FDA in 2014, is a 9-valent vaccine, protecting against HPV Types 6, 11, 16, 18, 31, 33, 45, 52, and 58. It targets the four HPV strains found in the quadrivalent version, along with five additional ones that are linked to cervical and other HPV-related cancers. Both versions of Gardasil are prophylactic, meant to be given to females or males before they become exposed to possible HPV infection through intimate contact.
Gardasil is one of the easiest and best ways to prevent a few dangerous and, to abuse the definition slightly, common cancers that afflict men and women. Without a doubt, the HPV vaccine prevents cancer.
Currently, in the United States, the Advisory Committee on Immunization Practices (ACIP) recommends that preteen girls and boys aged 11 or 12 are vaccinated against HPV. The immunization is also recommended for teenage girls and young women up to the age of 26 who did not receive it when they were younger, and teenage boys and young men up to the age of 21.
Let me sum this all up so that if you come away from this section with nothing else, you get this summary. HPV is a sexually transmitted disease. HPV causes 41,000 cancers a year in the USA alone. The HPV vaccine prevents becoming infected by HPV, which means you are protected from these cancers.
HPV vaccine has nearly wiped out HPV in the UK
Although I’ve previously written about solid evidence that shows a direct link between the HPV vaccine and the reduction in cancer incidence, nearly every week there are powerful articles that show us that the HPV vaccine is very effective.
For example, a new article, published in The Journal of Infectious Diseases, showed that the HPV vaccine program in the UK has led to significant reductions in the number of young women who are infected by cancer-causing HPV. The infections dropped by 86% in women aged 16-21 who were eligible for the HPV vaccine between 2010 and 2016.
Using DNA analysis of over 15,000 specimens, the researchers found reductions, between 2010/11 and 2016, in the following HPV types:
- HPV16/18 incidence decreased from 8.2% to 1.6% (an 80.5% reduction in incidence) in 16-18 year olds and from 14.0% to 1.6% (an 88.6% reduction) in 19-21 year olds.
- HPV31/33/45 incidence dropped from 6.5% to 0.6% (a 90.8% reduction) in 16-18 year olds and 8.6% to 2.6% (a 69.8% reduction) for 19-21 year olds.
In case you want to argue that the reduction is a result of just about anything but the vaccine, the researchers did compare the incidence of HPV infections between a group who were unvaccinated and another group who received the HPV vaccine. The incidence of HPV16/18 was 6X higher in the unvaccinated group, meaning they didn’t experience any reduction in risk of HPV infection compared to 2010/11.
Those of us who follow the studies about the HPV vaccine know that the argument will be “but, this doesn’t mean that cancer rates will drop – the vaccine is worthless.” I know that I’m going to employ a transitive argument, but if we know HPV is related to several cancers, and if we can prevent the HPV infection, we can prevent cancer. And, as I mentioned previously, we are already starting to get the evidence that the HPV vaccine is reducing the incidence of cancerous and pre-cancerous lesions.
In addition, the majority of vaccinations included in this study are the bivalent and quadrivalent vaccines that were prevalent at the time that the bulk of these girls received the vaccine. During the past few years, the 9-valent HPV vaccine has become more common, so even more cancer-causing HPV types will be blocked.
The authors thus concluded:
We demonstrate dramatic declines in the prevalence of vaccine HPV types in this population, similar to predictions from effectiveness models. We also demonstrate clear evidence of declining prevalence of HPV31/33/45, most likely attributable to cross-protection. As cervical screening is changing to HPV testing as a primary screen our data can inform decisions regarding HPV testing strategies. These data should also be used to inform assessments of the additional benefit of introducing the nonavalent (9-valent) vaccine to the national vaccination program.
Parents should know that the HPV vaccine prevents cancer
In a recent article, published in Cancer Epidemiology, Biomarkers & Prevention, parents of adolescents believed that the potential to prevent certain types of cancer is the best reason for their children to receive the HPV vaccine. Other reasons health care providers often had given to get the vaccine were far less persuasive.
In this study, the authors developed a best-to-worst scaling experiment to evaluate 11 reasons healthcare providers typically give to parents for the HPV vaccine. The study was administered in 2016 via a national, online survey of 1,177 parents of adolescents ages 11-17.
Parents said “it can prevent some types of cancer” was the best reason to get the HPV vaccination. Parents also felt that “it can prevent a common infection;” “it has lasting benefits;” and “it is a safe vaccine” were persuasive reasons, although not as much as preventing cancer.
Middle-ranked messages were “it works best at this age;” “it should be given before sexual contact;” “getting it on time may mean fewer shots;” and, “I think it is important.” I’m not sure that these are very convincing.
Parents said the worst reasons that healthcare providers could give included “it is a scientific breakthrough;” “I got it for my own child;” and “your child is due for it.”
Although this is a basic study, it reinforces the belief that doctors and nurses should concentrate their message on cancer prevention – it’s a medical issue that almost everyone focuses on. If we can’t convince parents that measles is dangerous, how can we convince them that HPV is dangerous when the infection itself is almost innocuous? An HPV infection rarely shows any symptoms until one is diagnosed with genital warts or cancer. I think saying “cancer” is enough of a message to be highly convincing.
And now that we have robust evidence that HPV infections drop with an HPV vaccine program, and equally robust evidence that HPV vaccinations reduce the incidence of cancers, parents need to know this. Spread the word!
Summary
Do I need to say anything more than this – the HPV vaccine prevents cancer.
We have powerful evidence it prevents HPV infections. We have solid evidence that HPV is linked to a bunch of dangerous cancers. And we have robust evidence that the HPV vaccine prevents cancer in the first cohort of women getting screened for cancer after receiving the vaccine.
Parents, please keep your children safe from cancer – get the HPV vaccine.
Notes
- Although this article focuses on the HPV vaccine, the hepatitis B vaccine is also important for the prevention of some cancers. The vaccine prevents hepatitis B viral infections, and chronic hepatitis B infections can lead to liver cirrhosis or cancer. Liver cancer is actually one of the few cancers in the USA where the incidence has increased over the past few years. And if you follow the anti-vaccine rhetoric, you know the hepatitis B vaccine is almost as controversial as the HPV vaccine.)
Citations
- Gilkey MB, Zhou M, McRee AL, Kornides ML, Bridges JFP. Parents’ Views on the Best and Worst Reasons for Guideline-Consistent HPV Vaccination. Cancer Epidemiol Biomarkers Prev. 2018 Jun 14. doi: 10.1158/1055-9965.EPI-17-1067. [Epub ahead of print] PubMed PMID: 29903744.
- Mesher D, Panwar K, Thomas SL, Edmundson C, Choi YH, Beddows S, Soldan K. The Impact of the National HPV Vaccination Program in England Using the Bivalent HPV Vaccine: Surveillance of Type-Specific HPV in Young Females, 2010–2016. The Journal of Infectious Diseases. 18 June 2018. jiy249. doi: 10.1093/infdis/jiy249.
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