HPV Vaccine vs. Vulvar, Vaginal Cancer
Study: Vaccine Thwarts HPV Precancerous Lesions in the Vulva and Vagina
May 17, 2007 -- Gardasil, a vaccine targeting human papillomavirus (HPV)
strains linked to cervical cancer, may also help prevent cancer of the vulva
That news comes from a three-year, international study of more than 18,000
women aged 16-26. The study appears in The Lancet.
Gardasil appears to be "highly effective" against precancerous
vulvar and vaginal lesions, especially in women who had never been exposed to
the HPV strains that Gardasil targets, write the researchers.
They included Jorma Paavonen, MD, of the obstetrics and gynecology
department at University Central Hospital in Helsinki, Finland.
Vulvar and vaginal cancer account for about 6% of gynecological cancers, and
while less common than cervical cancer, cases of vulvar and vaginal cancer are
rising. Surgery for those cancers can be mutilating, note the researchers.
HPV Vaccine Study
Paavonen and colleagues studied healthy young women in 24 countries in the
Americas, Europe, and Asia. None of the women was pregnant.
The researchers gave all of the women three shots over six months. The women
were randomly assigned to get Gardasil or an inactive shot (placebo).
The women got detailed physical checkups before receiving their first shot
and again two months and six months later. After that, they got two checkups
Since vulvar and vaginal cancers are relatively rare, the researchers
checked the women for signs of precancerous vulvar and vaginal lesions linked
to the HPV strains that Gardasil targets.
The HPV virus spreads through sexual contact. HPV usually doesn't cause
cancer, but some strains are linked to the leading cause of cervical, vulvar,
and vaginal cancer.
The researchers found that in women who hadn't been infected with two of the
four HPV strains targeted by Gardasil, the vaccine was 97% to 100% effective
against precancerous vulvar and vaginal lesions.
In women who had already been infected with those HPV strains when the study
started, the vaccine was 71% effective against the same precancerous
"With time, such vaccination could result in reduced rates of
HPV-related vulvar and vaginal cancers," write Paavonen and colleagues,
calling the vaccine "highly effective" against the precancerous
They note that the vaccine would likely be most effective in women who were
not yet sexually active. It's not known how long the vaccine's observed effects
last or whether booster shots are needed, Paavonen's team notes.
The study was funded by Merck, which makes Gardasil. Several of the
researchers work for or report financial ties to Merck.