The fear, uncertainty, and doubt (FUD) campaign, a disinformation tool used by the anti-vaccine religion for propaganda purposes, against the HPV vaccine would laughable if the lies didn’t put our young people at risk for cancer in the future. We already have circumstantial evidence that the HPV vaccine prevents cancer – but now we’re accumulating robust direct evidence that it can stop HPV-related cancers.
Despite the claims of anti-vaccine pseudoscientists, who spend their time trying to invent false claims about vaccine safety, HPV vaccine safety is nearly settled science, based on dozens of high quality clinical and epidemiological studies. Although the anti-vaccine religion would love you to believe that the vaccine kills their children, the scientific evidence decidedly refutes these assertions.
Anti-vaccine zealots illogically reject any circumstantial evidence that the HPV vaccine prevents cancer. That circumstantial evidence is based on powerful data that the vaccine prevents many strains of HPV infections, and we have similarly powerful data that many cancers are directly related to those same HPV infections – thus, if you stop the infection, it’s logical to accept that the vaccine will stop cancer. At least the logic makes sense to scientists, but apparently logic isn’t a top priority of pseudoscientific vaccine deniers.
Because HPV-related cancers can take years to show up – it’s a myth that cancers have some on-off switch that the causal factor instantly makes cancer appear – direct evidence has been difficult to research on whether HPV vaccines prevent cancer. But the HPV vaccine has been on the market for 10-15 years in most areas of the world, so if our hypothesis is correct, that the HPV vaccine prevents cancer, then maybe we can see a direct reduction in these cancers by now.
Guess what? We do have some of that direct evidence.
All about HPV vaccines
Many of you have read this section an enormous number of times, however, for some of the readers of this blog, this article might be their first bit of research into the human papillomavirus (HPV) vaccine. Thus, it’s important to get a brief overview of HPV and the vaccines. If you’ve read this section before, just skip to the next section if you want.
Genital and oral 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. 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:
These are all dangerous and disfiguring cancers that can be mostly prevented by the HPV cancer vaccine. If you’re a male, and you think that these are mostly female cancers, penile cancer can lead to amputation of your penis. Just think about that guys.
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 31,000 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 manufactured 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 deadly cancers that are related to HPV. It is definitely a cancer-preventing vaccine.
(Just a quick note. There are actually two cancer-preventing vaccines. Along with the HPV vaccines, the hepatitis B vaccine is also important for the prevention of some cancers. The vaccine prevents hepatitis B viral infections. 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.)
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.
HPV vaccine prevents cancer – paper 1
A new article by Luostarinen et al., published in the International Journal of Cancer, a high impact factor journal that focuses on, obviously, cancer, found a direct link between HPV vaccination status and risk of cancer.
The researchers looked for the presence of HPV-related cancers in 9,529 Finnish women who received the HPV vaccine vs. 17,838 women who had not. Here’s what they found – there were no HPV-related cancers in the vaccinated group and 10 in the age-matched unvaccinated group (see Note 1).
Hat tip to pro-vaccine Twitter person, Dan Kegel, @dkegel
Yes, the relative risk of HPV-related cancer in this study seems low. In fact, the incidence of these types of cancer is fairly low, though not zero, unlike the anti-vaccine math of all risks are rounded up to 100% and all benefits are rounded down to 0%. If we have a vaccine that can significantly reduce the risk of cancer from 10 to 0, that’s outstanding. And remember, the total number of HPV-related cancers in the USA is 31,000 – if we could reduce that to 15,000 or 10,000 or even 100 by the wide use of the vaccine, why not?
Additionally, this study was done around 10 years after the launch of the vaccine in Finland. If we extrapolate these results out to 20 or 30 years, the difference in risks of cancer in the unvaccinated and vaccinated groups will probably be much greater.
Anyway, I think this study provides solid evidence that the HPV vaccine prevents cancer.
HPV vaccine prevents cancer – paper 2
Another study in Japan shows a distinct and significant reduction in rates of cervical neoplasms in women who had received the HPV vaccine. The researchers studied in the incidence of abnormal cytology and histology with respect to HPV vaccination status in 5,924 women, 20 to 24, in the Miyagi Prefecture, Japan.
Among this group of women, the vaccination rate was really low, 16.9%, probably as a result of the Japanese Ministry of Health withdrawing recommendations for the HPV for ridiculous reasons. And to be perfectly clear, Japan did not “ban” the vaccine, a common trope of the anti-vaccine religion.
On to the actual results:
- The incidence rates of high grade squamous intraepithelial lesions were reduced by 82.5% in vaccinated women compared to unvaccinated ones.
- The incidence rates of cervical intraepithelial neoplasia (CIN) 1+ were reduced by 64.9% in women who were vaccinated against HPV.
- The incidence rates of CIN 2+ were reduced by 85.5% in vaccinated women.
These are all statistically significant reductions in incidence rates of pre-cancerous and cancerous lesions in young women. This population didn’t require waiting 20 or 30 years for information on the HPV vaccine effectiveness, but just a few years. Not only is this evidence that strongly supports our claims that the HPV vaccine prevents cancer, it also should prompt the Japanese Health Ministry to set aside the pseudoscience that caused them to remove recommendations for the vaccine, but to move forward and strongly recommend it to their young men and women.
HPV vaccine prevents cancer – a systematic review
In the one day after I wrote this post, a new article was published on 8 May 2018 that provides more robust evidence that the HPV vaccine prevents cancer. I doubt this will silence the anti-vaccine religion’s claims that we can’t “prove” (see Note 2) that the HPV can actually reduce the risk of HPV-related cancers.
In the article, published in the Cochrane Database of Systematic Reviews, I will get straight to the author’s conclusion:
There is high-certainty evidence that HPV vaccines protect against cervical precancer in adolescent girls and young women aged 15 to 26. The effect is higher for lesions associated with HPV16/18 than for lesions irrespective of HPV type. The effect is greater in those who are negative for hrHPV or HPV16/18 DNA at enrolment than those unselected for HPV DNA status. There is moderate-certainty evidence that HPV vaccines reduce CIN2+ in older women who are HPV16/18 negative, but not when they are unselected by HPV DNA status.
As I’ve stated many times, systematic reviews are at the pinnacle of the hierarchy of biomedical research – they collect and analyze data from numerous studies. A well-done systematic review essentially takes many clinical studies and rolls them up into one large study while removing bias and other issues.
In this review, the authors included 26 different clinical studies with over 73,000 participants. The researchers found significant reductions in incidence of cervical intraepithelial neoplasia (which can be a precursor of cervical cancer).
The HPV vaccine reduced the risk of these cervical pre-cancerous lesions, which are associated with HPV16 or HPV 18, from 341 to 157 for every 10,000 women. HPV vaccination also reduced the risk of any pre-cancerous lesion from 559 to 391 per 10,000 in this group.
Furthermore, the researchers reported that:
The risk of serious adverse events is similar between control and HPV vaccines in women of all ages (669 versus 656/10,000, RR 0.98 (0.92 to 1.05), high certainty). Mortality was 11/10,000 in control groups compared with 14/10,000 (9 to 22) with HPV vaccine (RR 1.29 [0.85 to 1.98]; low certainty).
Since these kind of scientific statements can be so carefully worded that it can be confusing, let me be clear. Adverse events are the same between vaccinated and unvaccinated groups. Furthermore, there were no individual adverse events that were statistically more frequent than in vaccinated than unvaccinated groups. Finally, there was no statistical difference in mortality rate between vaccinated and unvaccinated groups.
I know that someone is going to complain that “this is only pre-cancerous lesion data” – true enough, but as the authors stated, these data are only for about eight years post release of the vaccines, probably too early for cancers. However, pre-cancerous lesions lead to cancer. A reduction in these lesions lead to a reduction in cancer.
Summary
The body of evidence is growing that the HPV vaccine prevents cancer – as the timeline from the introduction of the vaccine grows into the second decade, researchers will be able to compare more and more populations of young women and men to determine their vaccination status along with cancer or pre-cancer incidence rates.
But the anti-vaccine zealots love pushing the fear, uncertainty, and doubt about the HPV vaccine. The say it doesn’t prevent cancer. They say it’s unsafe. They make up stories. However, we have several large, well-analyzed studies that have shown not just a small reduction in cancer incidence with the HPV vaccine, but a statistically significant large reduction – the science is powerful, despite their denialism.
We have overwhelming evidence that the vaccine is extremely safe. We have overwhelming evidence that the vaccine prevents HPV variants that cause numerous dangerous cancers in men and women. And now we have robust evidence that the vaccine is linked to a lower incidence of cancers.
Gardasil prevents cancer. Please vaccinate your kids against cancer. And if you’re a young adult, go to your doctor and get the vaccine for yourself. You are not a Marvel superhero, you have a high risk of cancer from HPV.
Notes
- The researchers also found significantly lower numbers for breast cancer, thyroid cancer, and melanoma. The authors didn’t include these cancers in the list of HPV-related cancers because there isn’t a lot of evidence of a link. However, studies published recently (here, here, and here all of which I reviewed) provided evidence that there might be a link between HPV and skin cancers – and this new study from Finland seems to show a significantly higher risk of melanoma in unvaccinated vs. vaccinated women. The HPV vaccine prevents cancer.
- I tire of writing this, but science doesn’t “prove” anything. Proofs are a bastion of mathematics and an argument for a mathematical statement. Even though mathematics is a branch of science, a mathematical proof can be shown to be true in all circumstances. Science, however, is provisional – a scientific consensus or theory is generally supported vast amounts of evidence. If contrary evidence, of similar quality and quantity, is presented to reverse our conclusions, then science moves in another direction. Science deniers constantly misuse this “provisional” basis of scientific principles, utilizing the argument from ignorance to claim that “well, science doesn’t really know.”
Citations
- Arbyn M, Xu L, Simoens C, Martin-Hirsch PPL. Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors. Cochrane Database of Systematic Reviews 2018, Issue 5. Art. No.: CD009069. DOI: 10.1002/14651858.CD009069.pub3.
- Chahoud J, Semaan A, Chen Y, Cao M, Rieber AG, Rady P, Tyring SK. Association Between β-Genus Human Papillomavirus and Cutaneous Squamous Cell Carcinoma in Immunocompetent Individuals-A Meta-analysis. JAMA Dermatol. 2016 Dec 1;152(12):1354-1364. doi: 10.1001/jamadermatol.2015.4530. PubMed PMID: 26720285.
- Hampras SS, Reed RA, Bezalel S, Cameron M, Cherpelis B, Fenske N, Sondak VK, Messina J, Tommasino M, Gheit T, Rollison DE. Cutaneous Human Papillomavirus Infection and Development of Subsequent Squamous Cell Carcinoma of the Skin. J Skin Cancer. 2016;2016:1368103. PubMed PMID: 27891253; PubMed Central PMCID: PMC5116506.
- Luostarinen T, Apter D, Dillner J, Eriksson T, Harjula K, Natunen K, Paavonen J, Pukkala E, Lehtinen M. Vaccination protects against invasive HPV-associated cancers. Int J Cancer. 2018 May 15;142(10):2186-2187. doi: 10.1002/ijc.31231. Epub 2018 Jan 4. PubMed PMID: 29280138.
- Nichols AJ, Allen AH, Shareef S, Badiavas EV, Kirsner RS, Ioannides T. Association of Human Papillomavirus Vaccine With the Development of Keratinocyte Carcinomas. JAMA Dermatol. 2017 Jun 1;153(6):571-574. doi: 10.1001/jamadermatol.2016.5703. PubMed PMID: 28196178; PubMed Central PMCID: PMC5540031.
- Ozawa N, Ito K, Tase T, Shibuya D, Metoki H, Yaegashi N. Lower Incidence of Cervical Intraepithelial Neoplasia among Young Women with Human Papillomavirus Vaccination in Miyagi, Japan. Tohoku J Exp Med. 2017 Dec;243(4):329-334. doi: 10.1620/tjem.243.329. PubMed PMID: 29269635.
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