Although 20 to 30 percent of sexually active Americans are infected with the virus that causes genital warts and it is found in 85 percent or more of cancers of the cervix, doctors say the wart epidemic is cause for concern but not alarm.
Most abnormalities tied to the warts can be detected by routine Pap smears and removed, say researchers, who are learning more and more about risk factors for developing cervical cancer and how to avoid them.
The most important safeguards are regular Pap smears and limiting the number of sex partners, they say. For teenagers, sex prior to age 18 increases the risk that such warts will cause precancerous lesions, they say.
In some cities today, half of all sexually active teens are infected with the sexually transmitted wart virus, or papilloma. Teenage girls under 18 are most vulnerable.
Alarmed by such findings, many women are asking their doctors to test them-and their daughters-for the wart virus in addition to taking the much less expensive Pap smear. And if the virus is detected, they are asking their doctors to remove infected cells surgically or by using heat or lasers, even if no visible warts or abnormal cells are present.
Many health experts say these women are panicking needlessly and point to another set of facts:
Most people who harbor the genital wart virus don`t develop warts, much less a precancerous condition known as dysplasia or cancers caused by the warts, said Dr. Mark Schiffmann, an epidemiologist at the National Cancer Institute who has been studying the virus for six years.
Women who do develop dysplasia are identified during routine Pap testing, in which a sample of cervical cells is examined under a microscope for the coil-shaped abnormalities that indicate the presence of the wart virus.
Worldwide, 600,000 women develop cervical cancer each year and 500,000 die from it. But only 13,000 American women get the disease each year and 5,000 die from it. Most of those who die hadn`t had regular Pap tests.
New research is shedding light on how the virus enters cervical cells and causes warts or cancer. Of the 70 wart virus strains that afflict humans, about 25 specialize in the genital tract. Two strains, numbers 16 and 18, are found in most cancers, Schiffmann said, but affected cells usually are removed in their precancerous stages after Pap tests detect them.
Several biotechnology companies are developing tests to detect genital wart viruses. Only one, the ViraPap test from Life Technologies Inc. of Gaithersburg, Md., has been approved by the Food and Drug Administration.
Although many men are infected with the genital wart virus, they rarely develop visible warts or cancer because penile skin tends to resist transformation by the virus.
”There`s no point in checking them for the virus because you can`t get rid of it,” said Dr. Alex Ferenczy, a professor of gynecology at McGill University in Montreal.
Women are more vulnerable to the virus because the cervix has a transition zone of cells that are undergoing cell division, Ferenczy said, and the virus exploits dividing cells to reproduce itself.
Today many people are asking whether genital warts are more common and whether young people are at a greater risk for cancer, he said.
Cervical cancer once was considered an old woman`s disease, Ferenczy said. In the 1960s, 9 percent of cervical cancers were found in women under 35. Now, he said, 25 percent of such cancers are found in women under 35.
An increasing number of teens are getting higher degrees of dysplasia, said Dr. Barbara Moscicki, an assistant professor of pediatrics at the University of California Medical School in San Francisco. What used to take 40 years to develop now takes 4 years.
Such trends are shedding light on the primary risk factors for cervical cancer, Schiffmann said.
The most important is the number of sexual partners. The more partners, Schiffmann said, the more likely a woman is to have wart virus DNA in her cervix.
Women who smoke more than 15 cigarettes a day double their risk of cervical cancer, Ferenczy said. Cervical secretions contain 40 times more metabolites of nicotine than blood, he said. A woman who smokes 10 cigarettes a day is exposing her cervix to the equivalent of 100 cigarettes a day.
Women who take birth control pills sometimes have more genital warts than women who use different methods of birth control, said Ferenczy, theorizing that the extra hormones stimulate the virus or that some women on the pill have more sexual partners.
Finally, some people may have vulnerable immune systems that are less adept at holding the viral infections in check, Schiffmann said.
Despite such worries, the American College of Obstetrics and Gynecology does not recommend that women be tested for wart virus infection. Instead it recommends that they get annual Pap smears that detect those viral infections that are actually causing trouble.
Other than that, the best advice for those who are sexually active is to aim at monogamy and use condoms.
The wart virus is an old enemy that only now is being fully explained by science, Schiffmann said. People should be concerned but, he said, ”we are not seeing a new horror unleashed on the world.”
