Q&A on HPV with Dr. Iain Morgan
In this Q&A, VCU Massey Cancer Center expert Iain Morgan, Ph.D., answers some frequently asked questions about the human papillomavirus (HPV), which, according to the Centers for Disease Control and Prevention (CDC), is the main cause of cervical cancer. HPV affects both men and women and is the most common sexually transmitted infection. Morgan, who is a member of Massey’s Cancer Molecular Genetics research program as well as the director of the VCU Philips Institute for Oral Health Research and a professor and chair of oral and craniofacial molecular biology at VCU, explains the virus, its vaccine and what you can do to prevent infection and decrease your risk of cervical cancer.
What is HPV and who is at risk of contracting it?
HPV (human papillomavirus) is a family of viruses consisting of double-stranded DNA. There are over 100 types of HPV that cause diseases ranging from simple hand and plantar warts to genital warts and several cancers, including cervical, anal, vulvar, head and neck cancer. The viruses that cause cancer are called high-risk HPV (HR-HPV). Everyone is at risk of being infected with HPV, and high-risk viruses that cause cervical cancer such as HPV16 and HPV18 are transmitted during sexual intercourse. It should be stressed that even if a couple remains monogamous for life, the woman is still at risk of developing cervical cancer.
How do I know if I have HPV?
Most people are infected with many different types of HPV, and they cause no harm for the most part. In most cases, even women infected with HR-HPV will not develop cancer. It is estimated that around 80 percent of sexually active (or formerly active) adults will have had an HR-HPV infection at some point in their life. One way that you can tell if you have a HR-HPV infection is by checking for the presence of viral DNA and this can be done on samples collected through a cervical screening test (also called pap smear) that can be done by your general practitioner or gynecologist. During the test, some cells from the cervix are collected and then checked for the presence of HPV DNA and also for early changes that, if ignored and not treated, could develop into cancer of the cervix. If the test shows any abnormality, you may require additional tests or treatment to prevent cervical cancer.
Can HPV be prevented?
If you are sexually active, it is difficult to protect against HPV infection. The current vaccine, discussed below, is only good for preventing an initial HPV infection. Once you are infected it seems likely that the virus can "hide" in your cells before going through a life cycle that can then create a problem in the infected cell.
How effective is the HPV vaccine and for how long does it last?
The HPV vaccine is incredibly successful. It stops over 99 percent of infections that the vaccine targets, according to current literature and as measured by reduction in HR-HPV disease and genital warts. Currently, we do not know how long it will last as its study is an ongoing process; vaccination only began in 2007-8, and to date the vaccine remains effective in those vaccinated in 2007-8. It is likely it will be effective for 10 years or longer.
Who should and should not get the HPV vaccine? Why?
It is recommended that all children aged 11-13 receive the vaccine. This is because they should be vaccinated prior to sexual activity. The vaccine generates antibodies that recognize a protein "coat" that the virus uses to protect its DNA. Attacking this coat and destroying it before the virus has a chance to infect a cell is the way the vaccine works. There is some evidence that women up to age 26 could benefit from the vaccine, as they may not have been exposed to all types of HPV viruses covered by the vaccine. There is a similar indication for men—men who have sex with men could benefit until age 26. The reasons for this are highly complex and based on statistical studies. There is likely no benefit for people in their late 20s and older as they will probably have been exposed to all viruses covered by the vaccine. In conclusion, the major targets for vaccination are adolescents before they become sexually active. Although this may be a difficult consideration for parents, the bottom line is that if your child is vaccinated now, it could prevent their death in 20-40 years.
Can HPV cause cancer?
Undoubtedly. Over 95 percent of cervical cancers have HPV present, and we now understand how these viruses cause cancer.
Can the HPV vaccine help prevent cervical cancer?
Yes, the vaccine will help prevent cervical cancer in those who are vaccinated before infection (i.e. adolescents). It should be mentioned here that a major increase in oral cancers caused by HPV is occurring, reaching epidemic proportions. Eighty percent of HPV positive oral cancer cases are in males, so it is very important that adolescent boys are also vaccinated.