The human papillomavirus, more commonly known as HPV, is a group of more than 150 related viruses. Some HPV types called “low-risk HPV” can cause warts and papillomas (non-cancerous tumors) and others categorized as “high-risk HPV” can cause cancers. HPV is a contagious virus and is so common that most people get it at some time in their lives. The lifetime risk of acquiring an HPV infection is approximately 80%. Most never know they are infected (no symptoms). About <5% will have significant pre–cancer and <1% will develop invasive cervical cancer.
HPV is most commonly transmitted by having vaginal, anal, or oral sex with someone who has the virus but intercourse is not necessary, as the virus can be transmitted by close intimate skin to skin contact. HPV can be passed on even when an infected person has no signs or symptoms. You can develop cancer years after you have sex with someone who is infected, making it hard to know when you first became infected. A mother who is infected with the virus can pass on the infection to her child during birth through the vaginal canal.
In 1979, a German scientist Harald Zur Hausen first discovered HPV, and over the next 25 years in his lab and many others, the major aspects of the HPV infections and the processes by which the virus causes cancers were elucidated. In 2008, Professor Zur Hausen was awarded the Nobel Prize in Medicine. It is now well accepted that virtually all cervical cancers, the overwhelming majority of oropharyngeal and anal cancers, and a major proportion of penile, vaginal and vulvar cancers are attributable to infection with high-risk (oncogenic) types of HPV. In most of the developing world, cervical cancer is a leading cause of cancer death in women (number 1 in most of Africa and second/third in most of Latin America and South Asia). In the United States and other developed countries, there is a significant increase in the rates of oropharyngeal cancers in men, and anal cancers in both men and women.
Because cervical premalignant disease is identifiable and treatable prior to the development of invasive cervical cancer, cancer prevention through routine examinations with Pap/HPV testing has been very effective in reducing cervical cancer incidence and mortality in the developed world. However, this approach is very expensive and is likely not feasible in resource / infrastructure poor regions of the developing world. Furthermore, the HPV-related oropharyngeal premalignant process is almost never identifiable prior to the development of invasive HPV-associated oropharyngeal cancer. Therefore, prevention of initial infection is most desirable option and vaccination to prevent infection is the most effective approach.
Fortunately, we now have very effective vaccines to prevent HPV infection. Pioneering work by Dr. Doug Lowy, current head of the National Cancer Institute, and others culminated in 2006 FDA approval. In 2007 a CDC recommendation was issued to offer these vaccines for pre-adolescent boys and girls 11 to 12 years of age to prevent HPV infection and the diseases that result from HPV. Catch-up vaccination is recommended for males and females through age 26. The vaccine is administered in three doses, with the second dose given one to two months after initiation and the third dose given six months after. The HPV vaccine can be given on the same day that the child receives the Tdap and meningococcal vaccines.
The HPV vaccines produce a higher immune response in preteens and young teens than they do in older teens and young adults, which is why it is very important for children to get vaccinated earlier than age 14. People should receive all three doses of the HPV vaccine series long before they are exposed to HPV. Research shows that HPV vaccine protection lasts for at least 10 years, and researchers believe that the protection should last longer. The best immune response has been shown at the preadolescent age range, meaning a stronger ability to protect.
The vaccine has been extensively monitored for safety. Common side effects include pain, redness or swelling at the injection site, and possible fainting. These effects go away on their own. Brief fainting spells can happen after any medical procedure, including vaccination. Some other reactions can include low fever, headache, nausea, vomiting, and muscle or joint pain. These are all considered mild reactions. No severe or unusual reactions have been listed. There is always a risk of allergic reaction with any vaccine. In the United States, the HPV vaccinations for males and females are fully covered by insurance companies under the Affordable Care Act and Vaccines for Children. Studies have shown that being vaccinated against HPV will not affect sexual behavior. For those who practice abstinence, there is no guarantee that a future partner will have made the same choice, leaving them open to future infection.
Despite this remarkable opportunity to prevent HPV-related cancers through the simple and safe step of vaccination, only 2 in 5 girls and only 1 in 5 boys in the U.S. are completing HPV vaccination series. The gravity of this missed opportunity to eradicate this disease from the next generation is that these cancers typically require aggressive multimodality cancer treatment including radiation and chemotherapy and sometimes mutilating surgeries. These treatments result in life-long impact on quality of life and daily functions, and if these cancers return after treatment they are typically incurable. Consequently, it is imperative that children complete the HPV vaccination series before their 13th birthday so that they are protected from being a victim of these cancers.
Jagannadha K. Sastry, Ph.D.
Kathleen M. Schmeler, M.D.
Erich M. Sturgis, M.D., M.P.H.
The University of Texas-M.D. Anderson Cancer Center, Houston, Texas