Promoting Sexual Health
HPV Vaccination: Safe, Effective Cancer Prevention
H
uman Papillomavirus (HPV) is a group of more than 150 related viruses, spread primarily through vaginal, anal, and oral sex. It is the most common sexually transmitted infection and an estimated six million Americans become infected every year. Those affected are often asymptomatic, or symptoms may develop years after the virus was contracted. Most sexually active individuals will contract HPV at some point in their lifetime, though most of these will be subclinical or unrecognized infections. An increased risk occurs with multiple sexual partners and in men who have sex with men. Condoms, while crucial, provide incomplete protection against HPV transmission. About 75% of the HPV types cause common warts on the skin, while other types are found mainly on the body’s mucus membranes, including the vagina, anus, mouth, and throat. Papillomas (warts) in these areas are often caused by low-risk HPV types that rarely cause cancer, but HPV types 16 and 18, in particular, are high-risk and can cause cancer in both men and women. In women, cervical cancer is the most common cancer linked to HPV, and 70% of these are due to types 16 and 18. Through a routine Pap smear and HPV testing, cervical dysplasia and cancer can often be found early and addressed. Vulvar and vaginal cancers also occur. In men, the most common HPV-related cancers are oral cancers. Despite a By Pamela Niksich, MD, MPH
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January/February 2019
decrease in tobacco use over the past two decades, the incidence of oropharyngeal cancer in men has begun to rise, in large part due to HPV associated cancers. Cohort studies from the 1990s suggested that approximately 50% of oropharyngeal cancers were attributable to HPV, while more recent studies suggest that HPV now accounts for 70 to 80% of cases in North America and Europe. The timing between exposure to HPV and the development of oropharyngeal cancer probably exceeds 10 years. There is no standard screening procedure to find these cancers early, or to look for the presence of HPV on oral mucosa. Many of these oral cancers are found incidentally during routine exam by a doctor, dentist, or dental hygienist. HPV also causes penile cancer, many of which start under the foreskin of the penis and
may be difficult to detect early. It can cause cancer of the anus in both men and women, though it is more common in HIV-positive individuals and in men who have sex with other men. Anal cytology testing, akin to a Pap smear to screen for cervical cancer, may be indicated for these populations. Annually, over 31,500 HPV attributable cancers are diagnosed in the United States, and over one-third of these are diagnosed in men. Approximately 4,100 women will die in 2018 from cervical cancer. Most HPV infections that lead to cancer can be prevented by vaccination before sexual debut. Since introduction of the HPV vaccine 10 years ago, infection with the HPV types that cause most genital warts and cancers have dropped 71% in teen girls. The HPV vaccine was FDA approved for females in 2006 and for males in 2010, and ACIP recommended HPV vaccine as a routine childhood vaccine in 2007 for females and and in 2011 for males. However, vaccine acceptance in the US has been slow, and in 2016, 50% of females and 38% of males had completed the vaccine series. This is well below the Healthy People 2020 goal of 80% vaccine series completion, and the HEDIS goal of two HPV vaccines before age 13 for both boys and girls. Nine-valent HPV vaccine helps to prevent disease caused by HPV types 6, 11, 16, 18, 31, 33, 45, 52, & 58. Two doses of the vaccine, separated by at least five months, are routinely recommended and given at age 11-12 years of age. The
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The Journal of the Twin Cities Medical Society