New HPV Vaccine Recommendations Could Have Multiple Benefits

From OncoLog, March 2012, Vol. 57, No. 3

New HPV Vaccine Recommendations Could Have Multiple Benefits

By Bryan Tutt

New recommendations for vaccination against human papillomavirus (HPV) are intended to prevent cervical cancer but may also decrease the incidence rates of other cancers.

Since the first HPV vaccine was approved in 2006, the U.S. Centers for Disease Control and Prevention (CDC) has recommended that girls be vaccinated against HPV beginning at age 11 years. However, vaccination rates among teenage girls have remained low, around 30%. To further decrease the spread of HPV and thus the incidence rate of cervical cancer, the CDC recently recommended the routine vaccination of boys beginning at age 11 or 12 years.

What’s the Difference?

Many patients know that there are two vaccines against the human papillomavirus (HPV), but most do not know the differences between the two. Physicians may find the information below useful in addressing patients’ questions about the two vaccines.

Gardasil (Merck & Co.) was approved by the U.S. Food and Drug Administration (FDA) in 2006 for girls and women.

Cervarix (GlaxoSmithKline) was approved by the FDA in 2009 for girls and women.

Both vaccines protect against the two most common cancer-causing HPV strains, HPV-16 and HPV-18; Gardasil also protects against HPV-6 and HPV-11, which cause genital warts. For this reason, in 2009 the FDA approved the use of Gardasil for boys and men. Cervarix is not approved in the United States for use in boys or men.

Both vaccines are given in a series of three injections over 6 months, and both vaccines have been reported to be effective and well tolerated.

“The reasoning for the new recommendation was to control cervical cancer by preventing the spread of the virus, but a side benefit could be a reduction in the number of oropharyngeal cancers as well,” said Erich M. Sturgis, M.D., M.P.H., a professor in the Department of Head and Neck Surgery and the Department of Epidemiology at The University of Texas MD Anderson Cancer Center. This benefit occurs because HPV-16 and HPV-18, the two virus strains that cause about 70% of all cervical cancers, also have been linked to cancers of the oropharynx as well as cancers of the anus, penis, vagina, and vulva.

While the cervix remains the most common site for cancers related to HPV, Dr. Sturgis said that by 2020 there will likely be more HPV-related oropharyngeal cancers than cervical cancers. A decline in cervical cancer rates has occurred over the past 30 years in developed countries because of the implementation of routine screening with gynecological examinations and Papanicolaou tests. Such screening often detects cervical dysplasia, which can be effectively treated before it develops into cancer.

A similar decline has occurred in the incidence rates of head and neck cancers related to tobacco and alcohol use. “As we’ve seen less smoking in the United States over the past 40 years, over the past 20 years we’ve seen declines in the incidences of virtually all head and neck cancers except oropharyngeal—tonsil and base of tongue—cancer,” Dr. Sturgis said. “This difference seems to be attributable to a dramatic rise in the incidence of the subgroup of oropharyngeal cancers related to HPV.”

It is believed that HPV is introduced into the oropharynx principally via oral sex. “There have probably been changes in sexual behavior in the past 30-plus years that have helped cause the higher incidence of HPV-related oropharyngeal cancers,” Dr. Sturgis said.

The prevention of oropharyngeal cancers is especially important because they are seldom detected in their early stages. Dr. Sturgis said that unlike cervical or anal dysplasia, premalignant oropharyngeal growths are not detectable by any current screening tests. Screening for the virus itself is unlikely to have any clinical relevance because most people are exposed to HPV without developing a chronic infection or subsequent HPV-related lesions. Instead, Dr. Sturgis said, “If a patient has symptoms like bleeding, ulceration, a neck mass, or pain in the throat that persist for 2 weeks, the patient should see an ear, nose, and throat doctor.”

The two most important steps in preventing oropharyngeal cancer are avoiding tobacco products and preventing HPV infection. “I would strongly recommend that boys and girls get vaccinated against HPV as recommended by the CDC,” Dr. Sturgis said.

For more information, contact Dr. Erich Sturgis at 713-792-6920.

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