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.
As I reported recently, the HPV vaccine uptake has not been as a high as many would like in the US. A recent retrospective epidemiological study of HPV cancers in Alberta, Canada, published in the Canadian Medical Association Journal OPEN, seemed to indicate that HPV related cancers have increased substantially in the study years from 1975 to 2009, prior to the widespread use of the HPV vaccine in Canada. This is another indicator that increasing the rate of HPV vaccination is important.
Just for a little background, genital human papillomavirus (HPV) is one of the most common sexually transmitted infections (STI). There are more than 40 HPV sub-types that can infect the genital areas of males and females. These same HPV types can also infect the mouth and throat. They are transmitted from personal contact during vaginal, anal or oral sex.
Some HPV subtypes, such as HPV-6 and HPV-11, can cause warts around the genitals or anus, but have low (but not 0) risk of causing cancers. However, the higher risk subtypes, such as HPV 16 and 18, not only cause approximately 70% of cervical cancers, but they cause most HPV-induced anal (95% linked to HPV), vulvar (50% linked), vaginal (65% linked), oropharyngeal (60% linked) and penile (35% linked) cancers. HPV is estimated to be the cause of nearly 5% of all new cancers across the world.
Much like ending smoking, preventing HPV infections are one of the few evidence-based methods known to modern medicine to reduce the actual risk of cancer.
According to the CDC, roughly 79 million Americans are infected with HPV–approximately 14 million Americans contract HPV every year. Most individuals don’t even know they have the infection until the onset of cancer. According to the Society of Obstetricians and Gynaecologists of Canada (SOGC), “it is estimated that 75% of Canadians will have at least one HPV infection in their lifetime.” SOGC also estimates that 10-30% of the Canadian adult population is infected with one of the HPV viruses, slightly lower than, but in line with the US rates.
The HPV quadrivalent vaccine, also known as Gardasil (or Silgard in Europe) can prevent infection by human papillomavirus, substantially reducing the risk of these types of cancers. An HPV bivalent vaccine, known as Cervarix, is used in some countries, but only provides protection again two of the subtypes most associated with cervical cancer.
The results of the Alberta epidemiological study showed some disturbing results.
- The incidence of HPV-related oropharyngeal cancers–located at the base of the tongue and tonsils–has increased 3.4% per year for men and 1.5% per year for women during the study period.
- The incidence of HPV-related anal cancers has increased 1.8% per year for men and 2.2% for women.
- As a comparison, in an effort to make a comparison to similar cancers, the rate of non-HPV related oral and lip cancers was stable.
According to the study authors, the increases in throat and anal cancers are “disturbing,” especially since early detection programs for those cancers are noticeably lacking in many parts of the world, including the USA and Canada. According to Lorraine Shack, Ph.D., lead author of the study, “the increasing incidence of these HPV-related cancers has been attributed to changes in lifestyle-related risk factors, most notably sexual behavior.”
Dr. Shack also stated that it will likely take decades for school-based HPV vaccination programs to have an impact on the HPV infection rate in a population. But the majority of women are exposed by the time they’re 25, “which is why it’s recommended you get vaccinated at a younger age.”
Part of the issue that there was an earlier push for vaccinating young girls than boys when Gardasil and other HPV vaccines were first released to the market, because the vaccines were initially indicated for use only for girls. Many of the areas of the world, including the USA, UK and Canada, vaccinating against HPV in young boys lags far behind the rate for young girls. A recent study by the US Centers for Disease Control and Prevention (CDC) reported that the HPV vaccine uptake for US girls, aged 13-17, was around 57.3%, whereas for the same group of boys, it was 34.6%.
A new editorial, by Gillian Prue, published in BMJ, urged increased uptake of the HPV vaccine in boys as probably being cost effective, but also because it simply works to prevent HPV related cancers.
If uptake is low in girls, the benefit of vaccinating boys is easily apparent. However, with high uptake in girls, vaccinating both sexes is less cost effective. Nevertheless, a European study that assessed male vaccination and all HPV carcinomas showed that vaccinating 12 year old boys and girls would be associated with substantial additional clinical benefits—namely, reduced incidence of HPV related genital warts and carcinomas, compared with vaccinating only girls. This additional benefit was noted even with an overall coverage of only 70%. In addition, a two dose schedule (in place of the current three dose schedule) will be introduced in the UK in September5; this will increase the cost effectiveness of a vaccinating boys as well as girls.
If you only focus on HPV related cancers in women, mostly cervical cancer, but also other types of cancer, then vaccinating boys also protects the women. If you then understand the growing incidence of HPV-related cancers that are found both in men and women, such as anal and oral cancers, and male specific cancers such as penile, then it makes sense to protect men too.
So, let me TL;DR this article. HPV causes cancer, more than just cervical cancer, in men and women. HPV vaccines, most notably Gardasil, prevents the HPV infection. Thus, Gardasil saves lives by saving men and women from cancer. Is this clear? I can’t make this much easier.
- Prue G. Vaccinate boys as well as girls against HPV: it works, and it may be cost effective. BMJ 2014;349:g4834 doi: 10.1136/bmj.g4834
- Shack L, Lau HY, Huang L, Doll C, Hao D. Trends in the incidence of human papillomavirus–related noncervical and cervical cancers in Alberta, Canada: a population-based study. CMAJ. 22 July 2014;2(3):E127-E132. doi: 10.9778/cmajo.20140005
- Stokley S, Jeyarajah J, Yankey D, Cano M, Gee J, Roark J, Curtis RC, Markowitz L; Immunization Services Division, National Center for Immunization and Respiratory Diseases, CDC. Human papillomavirus vaccination coverage among adolescents, 2007-2013, and postlicensure vaccine safety monitoring, 2006-2014 – United States. MMWR Morb Mortal Wkly Rep. 2014 Jul 25;63(29):620-4. PubMed PMID: 25055185.