June 23, 2000 -- A sexually transmitted virus that is responsible for many cases of cervical cancer can be found in a woman's body years before cancer develops. And researchers say that making tests for the human papillomavirus (HPV) part of routine cervical cancer screening can help detect these cancers early -- or at least identify women at risk so they can be followed closely.
"High-risk women could be identified by adding HPV ... testing to the cervical screening," says Nathalie Ylitalo, MD, the lead author of one of two new studies published in the medical journal The Lancet.
Up to 40 million Americans may be infected with HPV, according to the American Social Health Association. But, for most people who become infected, the immune system eliminates the virus on its own and no symptoms are ever apparent.
A common type of HPV, known as HPV 16, has been linked to many cases of cervical cancer. The current method for detecting cervical cancer is to look for changes in the cells on yearly Pap smears. The HPV test is available in the U.S., but is not approved for routine cervical cancer screening.
Ylitalo, of the Karolinska Institute in Stockholm, reports that women with the highest levels of HPV 16 in their bodies had a least a 30 times greater risk of cervical cancer than women who were not infected with the virus. Her research found that about one-fourth of women under age 25 with high levels of the virus developed cervical cancer within 15 years.
A second study, also by Swedish researchers, found that having high levels of the virus was linked to a 60 times increased risk of cervical cancer.
In both studies, the HPV infection was detectable in Pap smears taken an average of eight years before cancer developed, suggesting that an HPV test can identify women at high risk of cervical cancer years before any abnormal cells show up on their Pap smears.
Cervical cancer is the second leading cause of cancer-related deaths among women worldwide, after lung cancer. In the U.S., 15,000 women are diagnosed with the disease each year and 5,000 die. Worldwide, cervical cancer affects 500,000 women annually. According to the American Cancer Society and others, 50% to 60% of women who develop advanced cervical cancer have not had their recommended annual Pap smears in the previous three years, despite having had contact with a health care provider during that time.
So what should be done for women who have high levels of HPV 16 and are considered at risk of developing cervical cancer?
"These women "should definitely be followed closely with repeated Pap smears and HPV ... testing during the following year," Ylitalo tells WebMD. If cancerous changes are found, treatment should begin. Cervical cancer is typically treated by removing the cancerous tissue from the cervix, which usually cures the disease.
Because cervical cancer grows so slowly and because it is highly curable once detected, an HPV test can be a valuable addition to the Pap smear, says Hildegund C.J. Ertl, MD, PhD.
Ertl, a professor at the Wistar Institute in Philadelphia who was not involved in either study, says that while most women's bodies can rid them of HPV naturally, other women remain chronically infected, possibly due to genetic reasons. But it's impossible for doctors to know which women with HPV will rid themselves of the virus, she says. And, among those who don't, there is no sure way of knowing which ones will get cancer.
"Just having the virus is not going to make you have cancer," Ertl tells WebMD. "There has to be an additional event. It's just a question of time, and in some women it happens and in others it never happens."
- Human papillomavirus (HPV), a fairly common sexually transmitted virus, is believed to cause many cases of cervical cancer.
- New studies shows that women who test positive for HPV 16 have a far higher risk of getting cervical cancer. Researchers recommend that tests for the virus be added to women's annual Pap smears.
- Although HPV is often eliminated naturally by the body, some women carry the infection chronically, so screening may be a useful way to identify those at high risk of cervical cancer.