A new vaccine aimed at preventing cervical cancer is nearly 100 percent effective against the two types of the human papillomavirus (HPV) responsible for most cases of cervical cancer. Results of a nationwide study of the vaccine will be published in the May 10 issue of the New England Journal of Medicine.
Cervical cancer is the second most common cause of cancer deaths in women worldwide, resulting in nearly half a million diagnoses and 240,000 deaths each year. Every day in the United States ten women die from cervical cancer, according to Kevin Ault MD, associate professor of obstetrics and gynecology at Emory University School of Medicine, and one of the study authors.
But for the next generation of young women, a series of three shots of a new HPV vaccine marketed by Merck under the name Gardasil could make the difference in preventing cervical cancer. The vaccine targets HPV types 16 and 18, which cause about 70 percent of all cases of cervical cancer. It also targets HPV types 6 and 11, which together cause about 90 percent of all cases of genital warts.
Researchers at more than a dozen international medical centers evaluated the efficacy of quadrivalent vaccine targeting HPV types 6, 11, 16, 18 in more than 12,000 women ages 15 to 26 in 13 countries for nearly three years. They found a near 100 percent efficacy rate in prevention of HPV types 16 and 18.
"It's the first vaccine designed specifically to prevent cancer," says Dr. Ault, one of the authors of the study and a key researcher in the development of the vaccine. "The two main things to emphasize are the vaccine efficacy and the safety. These clinical trials have consistent efficacy around 98 percent. And severe reactions to the vaccine appear to be rare."
According to estimates from the Centers for Disease Control and Prevention (CDC) more than 20 million men and women in the US are infected with HPV, and more than six million new infections are reported each year, making it the most common sexually transmitted disease in the nation.
"Nearly all sexually active people are going to get exposed to the virus sometime during their lives," says Dr. Ault. "For most people, HPV causes no complications and goes away on its own. However, in some cases, if left untreated, certain high-risk types of HPV can lead to cervical cancer.
"The goal of the study was to see if we could prevent precancerous cases and we were 98 percent effective. Everyone who gets cancer goes through a pre-cancerous stage," says Ault. "There are about 50 to 60 million pap smears performed each year in the US, and about seven percent are abnormal. We spend about 3 billion dollars each year to find and treat these pre-cancerous stages caused by some type of HPV."
To date there is no vaccine specifically designed to treat disease that is already established. Dr. Ault explains the current HPV vaccine is meant to be a preventive or prophylactic vaccine--that's why it is given to adolescents.
Gardasil was approved by the U.S. Food and Drug Administration last year for use in females 9 to 26 years of age. While controversy has been raised about giving pre-adolescent girls a vaccine for a sexually transmitted disease, Dr. Ault argues, "young women, young girls make very good immune responses to this vaccine, so that will enhance their protection."
Researchers believe the vaccine will be effective in lowering a girl's lifetime risk of cervical cancer. To that end Merck launched the national "One Less" campaign last year, which encourages females eligible for the vaccine to begin their vaccination series of three shots over six months and to continue seeing their doctor for regular checkups and screenings.