Study: HPV vaccine works
Human papillomavirus (HPV) strains can cause several kinds of cancer, such as cervical, anal, and mouth and throat cancer, and 40 of the approximately 200 strains are spread through sexual contact – often early in life.
Fortunately, there is a vaccine to prevent it, and a new study shows it is working.
A new meta-analysis shows the HPV vaccine is very effective and is expected to lower the rate of cervical and other related cancers, said pediatrician Dawnnica K. Eastman, MD, of Seaside Pediatrics in West Yarmouth.
“The research was very thorough,” Dr. Eastman said. “It combined all the recent data from other studies.”
According to an article published in The Lancet in June, the researchers said they reviewed data from 60 million young men and women in 14 high-income nations. The research was funded by the World Health Organization and the Canadian Institutes of Health Research.
Key findings include:
- Five to eight years after vaccination, the presence of two HPV strains (16 and 18) that cause 70 percent of cervical cancer and precancerous lesions, dropped 83 percent, and three other high-risk strains (31, 33 and 45) decreased 54 percent for girls age 13-19.
- Five to eight years after vaccination, anal and genital wart diagnoses fell 67 percent for girls age 15 to 19 and 48 percent for boys age 15 to 19.
- Five to nine years after vaccination, CIN 2 lesions, a form of precancerous tissue caused by HPV infection, diminished 51 percent in girls age 15 to 19 and 31 percent among women age 20 to 24.
“It’s a really significant drop in precancerous lesions, which will definitely translate into a drop in cancer for girls,” Dr. Eastman said. “It showed a significant drop in genital warts for both sexes.”
HPV refers to more than 200 virus strains, of which more than 40 are spread through sexual activity, and some of those can cause genital warts or cancers of the cervix, anus, penis, vulva, mouth and throat, according to the National Cancer Institute of the federal National Institutes of Health.
When To Vaccinate
Nearly everyone contracts HPV sometime in their life, according to the Centers for Disease Control and Prevention, and most people will not develop cancer, precancerous lesions or genital warts. But, annually, about 33,700 Americans develop an HPV-related cancer. The CDC recommends the vaccine be given before sexual activity begins. If administered before age 15, two doses are needed – after 15, three doses are needed.
HPV vaccines have improved over the more than 10 years they’ve been in use, and the latest version, Gardasil 9, protects against the two strains that cause most cervical cancers, two more strains that cause 90 percent of genital warts, and five other strains that can cause cancer, according to the National Cancer Institute.
While cervical cancer is the most common cancer associated with HPV affecting women, oropharyngeal (mouth and throat) cancer is the most common such cancer among men.
According to the CDC, oropharyngeal cancer was considered mainly caused by tobacco and alcohol use, but now 70 percent of cases are associated with HPV, and some may be caused by a combination of HPV infection and tobacco and alcohol use. Annual cases of oropharyngeal cancer in American men (18,226, of which 12,885 are considered HPV-related) now outnumber cervical cancer cases in American women (11,866, of which are 10,751 considered HPV-related). However, when all types of HPV-related cancers are tabulated, women account for 20,260 cases annually, and men, 13,477 cases.
The rate of HPV-related oropharyngeal cancers in both men and women has been rising, according to the American Cancer Society. Dr. Eastman said prevention of these mouth and throat cancers is a good reason to vaccinate boys as well as girls.
“We don’t have screening for head and neck cancers” for boys and men, she said, unlike Pap smears for cervical cancer and precancerous lesions that teen girls and women can have done as part of routine gynecological exams.
Dr. Eastman estimated that about 60 to 70 percent of her teen patients get vaccinated, divided evenly between both sexes. Some parents hesitate to vaccinate their children, she said, although the vaccine has been proven to be safe. She also noted a study published in Pediatrics in 2018 that showed vaccination does not lead to teens being more sexually active – a concern of some adults.
HPV vaccination is offered at Seaside Pediatrics at every annual visit, Dr. Eastman said, and about one in four patients decline.
“I think teens are pretty savvy,” she said. “They see their friends who were vaccinated and it didn’t hurt them.”