Spermicides May Ease HPV Transmission
Animal Study Shows Ingredient in Spermicides May Boost Transmission of Human Papillomavirus
Next, the researchers focused on the use of carrageenan, a substance widely used as a thickening agent in foods and also used in some vaginal lubricants, including the brands Divine No. 9 and BIOglide.
The researchers use pure carrageenan, not the commercial lubricant formulas. They pretreated one group of mice with the spermicide and another group with both the spermicide and carrageenan. The third group wasn't pretreated with anything and wasn't exposed to the virus.
None of the animals exposed to both the spermicide and carrageenan got infected with HPV, Roberts says. But of those exposed just to the spermicide, "all were infected," he says.
Exactly how carrageenan protects isn’t certain, either, Roberts say. It may interfere with the HPV interaction at the cellular level, helping to prevent infection, he tells WebMD.
"We have no idea whether this is valid in humans," cautions Harper. Human trials of carrageenan are definitely in order, she says.
HPV and Cervical Cancer
In 2007, more than 11,000 women in the U.S. will learn they have cervical cancer, according to estimates from the American Cancer Society, and about 3,670 women will die from it this year.
Of the more than 100 HPV types, about 30 or so types can cause genital HPV infections. Of those, certain types are classified as "high risk" because they lead to abnormal cell changes and can cause genital cancers. HPV 16 and 18 are high risk -- thought to cause about 70% of all cervical cancers.
Most sexually active men and women do contract HPV at some point. Most won't have symptoms and the virus will typically clear on its own, often within two years or less. When it doesn't clear, the cells in the cervix can continue to change abnormally, with precancer or cancer the result if no treatment is received.
Though the new HPV vaccine, Gardasil, can help prevent infection, and another HPV vaccine is expected to be available soon, neither is a perfect solution because they don't protect against all HPV types. For that reason, Roberts and other public health experts believe it is important to consider other interventions against HPV to reduce the toll of cervical cancer.