The American Cancer Society warned Monday that cancer incidences associated with the sexually-transmitted human papillomavirus (HPV) increased between 2000 and 2009 and vaccine coverage, while increasing, isn't happening fast enough.
According to the report, published in the Journal of the National Cancer Institute, there was a significant increase in cancers often caused by HPV, including anal and oropharynx (mouth) cancers. There was a leveling off of cervical cancers during the time period. The news comes in stark contrast to overall cancer rates, which have been gradually declining during the past several decades.
Edgar Simard, an epidemiologist with the American Cancer Society and lead author of the report, says cancers caused by HPV will eventually begin declining because of the 2006 development of the HPV vaccine, commonly known as Gardasil. The vaccine is administered in three doses over the course of six months.
About 32 percent of girls aged 13 to 17 had taken all three doses of the vaccine as of 2010, a 64 percent increase (11.5 percentage points) from 2008. About two thirds of girls who took at least one dose of the vaccine finished the three-shot course. The Centers for Disease Control just recently recommended the HPV vaccine for men and boys, but does not yet have numbers on the percentage of boys vaccinated.
Simard says the increased number of girls receiving the vaccine is encouraging, but it will take decades until there is a significant decrease in the number of cancer cases caused by HPV.
"I'd say [a decline] is probably 15-20 years out for cervical cancer, because some of those cases develop among women in their late 20s and early 30s," he says. "For other cancers, it's much longer, because they take decades to develop."
The virus is one of the most common sexually transmitted infections—it infects about 50 percent of sexually active people, according to the Centers for Disease Control. Often, the disease is asymptomatic, but it can cause genital warts and several different types of cancers. It is estimated to cause about 12,000 cases of cervical cancer in the United States each year and several thousand more cases of vulvar, vaginal, anal, and penile cancers.
HPV vaccination rates in the United States have lagged behind those in other countries, such as Canada (85 percent), Mexico (67 percent), and the United Kingdom (70 percent). The uninsured remain particularly unlikely to get the vaccine: Just 14 percent of uninsured adolescent girls were vaccinated by 2010, according to the report.
"We need to find ways to have greater vaccine uptake," Simard says. "Coverage is still quite low compared to other adolescent vaccines, it's low relative to Canada and Mexico. Most everyone will be exposed to HPV throughout their lives, so we could do more to encourage the message that people should get vaccinated."