Cervical Cancer Vaccine on the Way
Study Says Vaccine Also Prevents Genital Warts
April 6, 2005 - A vaccine that could prevent both cervical cancer and
genital warts may be available as early as next year. In a newly reported
study, the vaccine was found to be 90% effective for preventing the majority of
viral infections that cause these sexually transmitted diseases.
Experts say the highly anticipated cervical cancer vaccine could have a huge
impact on the thousands of women with this cancer worldwide. About 500,000
women get cervical cancer each year, mostly in developing nations without
screening programs. Half end up dying from the disease.
"This is a very exciting time," researcher Luisa L. Villa, PhD,
tells WebMD. "We have shown that this vaccine is highly effective.
Universal vaccination could lead to dramatic declines in cervical
100% Protective Against Disease
Cervical cancer is almost exclusively caused by the human papilloma virus,
or HPV. There are more than 100 types, but only certain high-risk strains cause
lesions that over time can develop into cancer if not treated.
Routine screening with Pap smears can detect abnormalities and prevent
cervical cancer. The widespread use of Pap smears has been shown to reduce
cervical cancer rates in the U.S. It is recommended that women begin screening
within three years of becoming sexually active or age 21, whichever comes
The HPV vaccine targets four high-risk strains of HPV -- types 16, 18, 6,
and 11. About 70% of cervical cancers are caused by infection with HPV 16 and
HPV 18, and 90% of genital warts are caused by infection with types 6 and
The study, which was funded by the vaccine's manufacturer, Merck, involved
277 sexually active young women who were given the HPV vaccine and 275 sexually
active women who were given a placebo vaccine. The women showed no prior
abnormalities on cervical exams.
The vaccinated group received two booster shots within six months of the
initial vaccination. The group was followed for three years. During that time
the women had repeated Pap tests. HPV tests were also performed. HPV tests
detect the DNA of cancer-causing types of HPV.
Thirty-five women in the placebo group developed persistent infection with
one of the HPV strains, compared with four women who received the vaccine.
There were six diseases associated with HPV infection in the placebo group
and none in the vaccine group.
The vaccine reduced persistent HPV infection by 90% and was 100% effective
three years later in preventing precancerous cervical lesions and genital
warts. The findings are published in the April 7 online edition of The
Researchers are developing many vaccines to prevent different cancers, but
the HPV vaccine is considered the closest to approval.
Merck is one of two drug giants racing to develop an effective and safe HPV
vaccine. GlaxoSmithKline also reported promising results late last year in a
study involving 1,100 young women. The vaccine used in that trial targeted HPV
strains that cause cervical cancer but not genital warts.