Vaccinating Against HPV: How Important Is It?
Some confusion exists as to how and when the HPV vaccine should be used to prevent cancer
In August 2010, Actor Michael Douglas announced that he had been diagnosed with advanced-stage oropharyngeal cancer by doctors in Montreal, Canada. For the next 6 months, he underwent aggressive chemotherapy and radiation treatment.
By January 2011, Mr. Douglas reported that he was cancer-free. Recently, the actor was interviewed by a British newspaper and was quoted as saying that his type of cancer could be caused by oncogenic strains of the human papillomavirus (HPV), a sexually transmitted pathogen, despite earlier reports that his cancer was caused by years of intense stress and a lifestyle of heavy smoking and alcohol consumption.
“Oropharyngeal cancer used to be a disease mostly found in people 60 years and older who abused alcohol and tobacco products,” says Brian Benson, MD, Co-chief of the Head and Neck Surgical Oncology Program at the John Theurer Cancer Center and Director of the VOICE Center, Hackensack University Medical Center, Hackensack, NJ.
“However, in my practice, we have observed a shift in the disease's age demographic and clinical features.” Benson now sees younger patients with HPV-associated oropharyngeal cancer, which although is still categorized as squamous cell carcinoma, has a different clinical behavior than the traditional disease seen in older patients.
Dr. Benson explains that, generally, patients in the shifted demographic are presenting with a neck mass at a younger age (40 to 50 years instead of 60 years and older). These tumors also behave differently than their alcohol- and tobacco-induced counterparts. First, tumors are 5 mm foci and appear in the tonsil or at the base of the tongue.
Also, in some cases, metastasis occurs earlier in the younger group than in their traditional alcohol- and tobacco-induced counterparts. However, tumors in the younger demographic tend to respond better to treatment and the prognosis is generally better across all treatment modalities.
There are more than 100 HPV types but only 15 of them have been proven in research studies to cause cervical cancer; these are often referred to as “high-risk” HPV types. Other HPV types can cause benign genital warts and are referred to as “low-risk” (eg, HPV 6 and 11). HPV types 16 and 18 are the most common cancer-causing viruses. HPV 16 and HPV 18 cause cervical and other anogenital cancers, whereas HPV 16 also causes oropharyngeal cancer.1,2
The HPV Vaccine: What Does it Prevent?
There are currently two HPV vaccines on the market. Cervarix, produced by the pharmaceutical company GlaxoSmithKline (Philadelphia, PA), prevents infections from HPV types 16, 18, 6, and 11, whereas Gardasil, produced by Merck (Whitehouse Station, NJ), prevents infections by HPV types 16 and 18. Vaccinating against HPV 16 and 18 confers immune resistance to infection by these two oncogenic strains, and therefore neutralizes their ability to cause cervical and other anogenital cancers, as well as oropharyngeal cancer.
But do these vaccines really work? “Yes, the HPV vaccine prevents individuals from being infected with specific types of HPV that are known to cause cancer.” said Camille Ragin, PhD, MPH, Associate Professor of the Cancer Prevention and Control Program, Fox Chase Cancer Center, Philadelphia, PA.
Many people are exposed to HPV through sexual activity, although a majority of those infected successfully receive treatment for the infection; however, the individuals who do not seek treatment can go on to develop cervical cancer or tonsil cancer. “We should vaccinate against HPV infection because a patient diagnosed with HPV-associated cancer has most likely exposed their partner, who may become infected and eventually develop the same cancer or another HPV-associated cancer,” says Dr. Benson.
Vaccinate Males and Females?
One of the most frequently asked questions about the HPV vaccine is whether it should be administered to both males and females.
Gail Schewitz, MD, a Pediatrician with the Metropolitan Pediatric Group in Teaneck, NJ, vaccinates approximately 70% of her female patients and 30% of her male patients. She says she does so because “the HPV vaccine is the first shot that can actually prevent cancer, and if you want to prevent the infection, and potentially HPV-associated cancers, you have to vaccinate both girls and boys,” she said in an interview with ChemotherapyAdvisor.com.
Dr. Schewitz started vaccinating boys in 2012 when the U.S. Food and Drug Administration (FDA) recommended the vaccine to prevent rectal and oral cancers. Before 2012, the FDA recommended vaccinating boys only to prevent them from transmitting HPV to females.3
Dr. Ragin also agrees with the FDA recommendations, for two reasons. “First, the HPV vaccine will help to reduce the risk of most cervical, vaginal, and vulvar cancers in women. Also, since HPV is acquired by sexual activity, vaccinating boys would also help to prevent HPV transmission. Second, HPV 16 has been shown to be associated with cancers of the oropharynx and tonsils. These cancers arise in both males and females.”
The FDA recommends vaccinating boys and girls at the age of 11 or 12 years, but Dr. Schewitz begins vaccinating a little bit later. “We vaccinate girls starting at age 13, and boys starting at age 15,” she says. The reason for delaying the vaccinations is because her patient population is generally not sexually active at age 11 or 12.
There is a lot of debate about when to administer the HPV vaccination. Since HPV infection is a sexually transmitted disease, some religious groups argue that vaccinating children earlier would lead them to become sexually active at a younger age. However, experts agree that vaccinating children earlier is the most effective method, because the vaccine must be given prior to HPV exposure. The FDA recommends that both Cervarix and Gardasil can be administered to females aged 9 to 26 years and Gardasil is FDA-approved for males between the ages of 9 and 26.
Is Age 9 Too Young to Vaccinate Against HPV?
According to Dr. Benson, people may become infected with HPV when they are 20 years of age, but not develop cancer until many years later. It is hypothesized that during this long time period, genetic mutations are being accumulated until they reach that critical point when infected tissue transforms into carcinoma. Because of this long incubation period, Dr. Benson says, “We are not at a stage where we are able to objectively assess whether the vaccine is having an effect of preventing HPV-associated cancers.”
“We are vaccinating 12-year-old children when they might not develop cancer until they are 40. So, we don't anticipate that we will see a significant decline in disease incidence for decades,” Dr. Benson adds. Despite this long waiting period, Dr. Benson explains that because there has been a decline in the incidence of cervical cancer since vaccination began, and since both cervical cancer and oropharyngeal cancer are HPV-associated, he expects there will be a similar trend in oropharyngeal cancer.
Furthermore, some parents of Dr. Schewitz's patients have objected to their children being vaccinated against HPV, citing that the vaccine is “too new and is not absolutely required.” Despite these objections, Dr. Schewitz predicts that she will vaccinate an increasing percentage of her patients during the next several years.
“This is due to the fact that as more people become aware of the vaccine, they will realize that it is safe and preventive,” she said. With Gardasil, in particular, she has not witnessed a single allergic reaction since she began administering the vaccine in 2006.
“Vaccination does not prevent all HPV-associated cancers in individuals who receive the shot,” concludes Dr. Schewitz, “but anything that can help prevent cancer is worth doing.”
1. National Cancer Institute. “HPV and Cancer.” Found at http://www.cancer.gov/cancertopics/factsheet/Risk/HPV. Accessed on July 8, 2013.
2. The Cleveland Clinic. “Oropharyngeal Cancer Overview”. Found at http://my.clevelandclinic.org/disorders/oropharyngeal_cancer/hic_oropharyngeal_cancer.aspx. Accessed on July 8, 2013.
3. U.S. Food and Drug Administration. “Gardasil.” Found at http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/UCM094042. Accessed on July 8. 2013.