New vaccine shows promise for preventing cervical cancer and other female cancers

The Food and Drug Administration in June announced the approval of Gardasil, the first vaccine developed to prevent cervical cancer due to certain forms of human papillomavirus.

Research has indicated that the vaccine could also be helpful in preventing other female cancers associated with HPV.

Gardasil is approved for use in girls and women 9-26 years of age and is most effective when given before the onset of sexual activity. The vaccine is administered as three injections over a six-month period and contains no live virus. Since the vaccine is new, the FDA is still researching how long it protects against HPV and whether a booster is needed after a few years.

The vaccine is made by Merck & Co. and is available through St. John’s OB/GYNs and family medicine physicians.

HPV is the most common sexually transmitted infection in the U.S. The Centers for Disease Control and Prevention estimates that more than half of all sexually active men and women become infected with HPV at some point in their lives. An estimated 20 million men and women in the U.S. are infected, but for the most part, the virus shows no symptoms and goes away on its own.

“This virus is very common in the population,” says St. John’s OB/GYN Christina Litherland, M.D. “Over a three-year period, 60 percent of women will test positive at one point. At any point, approximately 30 percent of the female population will test positive. Obviously, this means a large number of women will clear their infection spontaneously. The difficulty is, you can't predict who will and who won't spontaneously clear the infection.”

Christina Litherland, M.D.

Some HPV types can cause abnormal cells on the lining of the cervix that years later, can turn into cancer. On average, there are nearly 10,000 new cases of cervical cancer and nearly 4,000 deaths attributed to it in the U.S. each year. Other HPV types can cause genital warts, which must be removed by a physician.

“The vaccine protects against HPV types 6 and 11 (which cause 70 percent of genital warts) and types 16 and 18 (which cause 90 percent of cervical dysplasia, or abnormal cells). Vaccination could therefore prevent a large number of cases of cervical dysplasia,” Dr. Litherland says.

THE KEY TO VACCINATING

“The key will be vaccinating before sexual activity. Once you are exposed
to this virus, if you don't clear the infection on your own, the vaccine won't protect you against the HPV type you have already been exposed to,”
Dr. Litherland says.

Vaccination before the onset of sexual activity can prevent invasive gynecological procedures needed to treat dysplasia caused by HPV later in life, she adds. “If HPV infection is prevented, the rate of abnormal Pap screenings will decrease and women won’t need to have a colposcopy/biopsy to determine if dysplasia is present on the cervix,” Dr. Litherland says.

Moderate to severe dysplasia is often treated with the LEEP (loop electrical excision procedure). This is a procedure where the abnormal cells on the cervix are removed. One risk of this procedure (although uncommon) is cervical incompetence, which can cause miscarriage and premature delivery in pregnancy. Other risks include infection and bleeding.

Gardasil does not protect against the less common HPV types not included in the vaccine, so regular Pap screenings remain critically important to detect precancerous changes in the cervix to allow treatment before cancer develops.