CINCINNATI—Last week a federal advisory committee recommended that boys and young men should be vaccinated against human papillomavirus, or HPV, the sexually transmitted virus that can lead to cervical cancer in women and that is being implicated in a small but growing incidence of throat cancer among both men and women.
Yash Patil, MD, assistant professor of otolaryngology at the University of Cincinnati (UC) and an otolaryngologist with UC Health and the UC Neuroscience Institute, says that although the actual rate of head and neck cancer in the general population is low, leading to about 15,000 deaths in the United States each year, he is seeing increasing numbers of patients with oropharyngeal cancer who test positive for the HPV virus. Oropharyngeal cancers occur on the tonsils and the base of the tongue.
"Head and neck cancer typically affects patients who smoke and drink excessive amounts of alcohol,” Dr. Patil says. "But with HPV virus, we’re starting to find that we have an entirely different subset of patients who are younger and healthier and who have never smoked or drunk excessively. Almost three-quarters of samples collected from patients who develop oropharyngeal show positivity for HPV.”
Ohio State University researchers reported in the Journal of Clinical Oncology (published online before print on Oct. 3, 2011) that in a sampling of 271 patients who were diagnosed with oropharyngeal cancer from 1984 to 2004, HPV was found in 16 percent of tumor samples from the 1980s and in 72 percent of samples collected after 2000. The researchers estimated that the incidence of these cancers has increased from 0.8 per 100,000 people in 1988 to 2.6 per 100,000 people in 2004.
Signs of HPV infection have been seen in tissue samples taken from healthy people as well as from patients with head and neck cancer. However, the vast majority of individuals who test positive for HPV will not go on to develop cancer.
Some scientists suggest that throat cancer caused by HPV is emerging as a sexually transmitted disease, the result of increasing acceptance of oral sex among young people. The Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention, which recommended vaccinations for boys and young men, said the vaccinations would protect against throat (and anal) cancers that can result from sexual activity.
Nevertheless, Patil believes it is too early to say that oropharyngeal cancer is a type of sexually transmitted disease.
"We also see other diseases in the throat caused by HPV infection, specifically in very young children, who obviously have no sexual history,” Patil said. "In these instances, the mode of spread might be maternal-fetal.
"There are different subtypes of HPV,” he added, "and the mechanism of transmission of HPV is not completely understood.”
Nevertheless, the public should be aware of the link between HPV infection and oropharyngeal cancer, Patil said. "Younger people need to know that HPV is a sexually transmitted disease and that most certainly they should be cautious of choosing their lifestyle or their sexual partner.”
Physicians, he continued, should be aware of the link between HPV infection and oropharyngeal cancer. The most common symptom of cancer of the throat is not a sore throat but rather an enlarged lymph node, the result of metastasis from the throat.
"Most people are aware that smoking is carcinogenic,” Patil said. "But people are not thinking of cancer when they see younger patients with HPV infection. Nobody is thinking about the fact that this patient does not have a sore throat, or that the lump in their neck isn’t just a swollen lymph node caused by infection. These patients actually have a cancer that has spread to a lymph node. The cancer has already spread before the throat cancer is diagnosed.”
HPV is currently being studied by researchers in the departments of otolaryngology and radiation oncology and the internal medicine department’s division of hematology oncology, along with colleagues at Cincinnati Children’s Hospital Medical Center. Any time a cancer is removed or biopsied at UC Health University Hospital or Cincinnati Children’s, tissue is collected and preserved in a tumor bank. This allows individual cancers to be used multiple times, in current and future studies.
Patients who are diagnosed with oropharyngeal cancer at UCNI are tested for HPV positivity. "We know that this subset of patients responds differently to treatment,” Patil says. "The presence of HPV in these patients helps guide our treatment.”
Two vaccines, Gardasil and Cervarix, are approved by the FDA for protection against genital warts and cervical cancer in girls. They must be administered prior to a first exposure, and thus are generally recommended for girls who are 11 to 12.
Although the vaccines are not approved for protection against throat cancer, the vaccine advisory committee has said that boys could be vaccinated against the disease if they or their parents wished. The committee recommended vaccinations for boys ages 11 and 12 and for males 13 through 21 who had not already had all three shots. The committee said boys as young as 9 and men 22 to 26 could receive the vaccine.
The vaccine cannot provide benefits to an adult who already has developed throat cancer.
The HPV vaccine, like all vaccines, creates a societal benefit in that vaccinated individuals, in addition to being protected themselves, cannot spread the virus to others.
"If we appropriately vaccinate a subset of patients, that tends to result in a herd immunity,” Patil says. "We know that if we vaccinate a large population, even those individuals who are not vaccinated are helped.”
For an appointment with UC Health otolaryngologist call 513-475-8400.
Ohio State study: http://jco.ascopubs.org/content/early/2011/10/03/JCO.2011.36.4596.abstract