Thumbs Up for Cervical Cancer Vaccine
FDA Advisory Panel Recommends Approval of Vaccine Called Gardasil
May 18, 2006 -- Government advisors strongly backed U.S. approval of the
first cervical cancer
vaccine Thursday, saying it appeared highly effective in preventing the
infection that causes it.
The vaccine, called Gardasil, was nearly 100% successful in protecting young
women against new infections with two types of human papillomavirus (HPV), a
common sexually transmitted virus known to cause cervical cancer. These two types
of HPV are responsible for 70% of cervical cancers.
Health groups called the vaccine a potential boon for preventing cervical
cancer, which is expected to be diagnosed in 9,710 U.S. women this year and
kill roughly 3,700.
But experts warned that the vaccine only offers protection for women who
have not already been infected. HPV infection is quite common for men and
women, and many people do not realize that they are infected. Also, cervical
cancers are caused by other factors.
It suggests Gardasil is likely to have the most benefit only when given to
adolescents before their first sexual intercourse, they said.
Still, a panel of FDA advisors praised Merck -- the maker of Gardasil -- for
its study of the vaccine in approximately 27,000 women in 33 countries.
“This is certainly a wonderful, good step,” said Monica M. Farley, MD, the
panel’s acting chair and a professor of medicine at Emory University in
The panel voted unanimously that the vaccine is safe and effective in
preventing precancerous lesions in women between 16 and 26 years of age.
Studies also suggested that it boosts HPV immunity in 9- to 15-year-olds, a
group that would ultimately be the target of an effective immunization
campaign, experts said.
Gardasil is given in a series of three injections over six months. Merck’s
studies showed that the protocol prevented the development of precancerous
lesions in 98% or more of women up to 3.5 years after vaccination -- as long as
women were infection-free when they received it.
HPV types also cause genital wartsg in both females and males. The vaccine contains
two virus types blamed for most cases of the lesions.
But the vaccine doesn’t work against a virus already infecting the body. Its
purpose is for prevention, not treatment. At the same time, there is no simple
and cheap test for the presence of HPV infection. That means that many women
who get the vaccine may already be carrying one of the several different types
FDA scientists said their analysis showed that vaccination of unscreened
women in doctors’ offices would likely cut the rate of precancerous lesions by
40%, since many are likely to already carry infections with one or more HPV
While praising its potential, several experts expressed concern that
overconfidence in the vaccine could undo years of progress in promoting cervical
cancer screening in women using Pap tests. The tests are the only
reliable way to detect the presence of abnormal cervical cells that may be
cancerous or precancerous.
Eliav Barr, MD, Merck’s senior director for vaccines and biologics, pledged
that the company would not promote Gardasil as an alternative to Pap testing.
“This vaccine is not a replacement for cervical cancer screening, and I
think that that’s clear,” Barr said.