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A study of almost 3.5 million people confirmed that immunization against the human papillomavirus (HPV) lowers the chances of developing cancers caused by HPV. This includes head and neck cancer in men and boys and cervical cancer in women and girls.

¡°We have known that the HPV vaccine decreases rates of oral HPV infection, but this study shows that in boys and men in particular, vaccination decreases the risk of HPV-related oropharyngeal head and neck cancers,¡± said ASCO expert Glenn J. Hanna, MD, director of the Center for Cancer Therapeutic Innovation at the Dana-Farber Cancer institute. ¡°HPV vaccination is cancer prevention.¡±??

The findings were presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting.

HPV causes six types of cancer

HPV is a common virus that is spread by skin-to-skin contact. Over time, some types of HPV can cause cells to grow out of control and turn into cancer.

The HPV vaccine protects against some types of HPV that can cause cancer. Immunization against HPV is recommended for most people between the ages of 9 and 26, and people up to age 45 can be immunized. However, there are still many children and adults in the United States who have not received the two or three shots needed to be protected against cancer.

¡°°Õ³ó±ð that in 2022, less than 60% of children ages 15 to 17 had been vaccinated for HPV, suggesting that a large portion of the population is more vulnerable to HPV infection and, in turn, more vulnerable to the development of HPV-related cancers,¡± said lead study author Jefferson DeKloe, a research fellow at Thomas Jefferson University in Philadelphia, Pennsylvania.

The HPV vaccine was approved in the United States in 2006. Since then, many studies have shown that protection against HPV lowers the risk of cervical cancer. However, other cancers can be caused by HPV, including head and neck cancer, as well as cancers of the anus, penis, vulva, and vagina. This study compared cancer risk between people who received the HPV vaccine and those who did not.

Immunity to HPV cuts risk of all HPV-related cancers

Researchers looked at data from 3,413,077 people in the United States. The people were between 9 and 39 years old and had received an immunization between January 1, 2010, and December 31, 2023. The study compared the rates of HPV-related cancer in people who had been immunized against HPV and those who had not. Their average age was 21 years.

People who were immunized against HPV had a lower risk of developing HPV-related cancers than those who were not immunized.

• In men and boys who were immunized, there were 26 cases of HPV-related cancer. In comparison, there were 57 cases of HPV-related cancer among people who were not immunized.
• In women and girls who were immunized, there were 109 cases of HPV-related cancer. In comparison, there were 149 cases among people who were not immunized.

Because many HPV-related cancers are more common in older adults, this research will continue to study what happens to people older than 39 years old.

Less head and neck cancer in men and boys

HPV immunization also lowered the risk of developing head and neck cancer among men and boys. There were 21 cases of head and neck cancer among immunized men and boys. In comparison, there were 48 cases among men and boys who were not immunized.?

Less cervical cancer in women and girls

The HPV vaccine protected women and girls against cervical cancer. There were 70 cases of cervical cancer among immunized women and girls. In comparison, there were 99 cases of cervical cancer among women and girls who were not immunized.

Immunized women who had never had an abnormal result during a Pap test were also less likely to develop cervical dysplasia. Cervical dysplasia is when abnormal cells grow on the cervix. It is not cancer but can eventually turn into cancer and requires invasive treatment.

When should children and teens be immunized for HPV?

¡°This study illustrates the profound impact of preventive immunization strategies on the burden of HPV-related cancers, including oropharynx cancers. I routinely discuss vaccination of eligible household members during patient visits, and this data supports our continued efforts (both in the clinic and with public policy) to make this vaccine accessible to all eligible individuals,¡± said ASCO expert Cristina Rodriguez, MD, a professor and oncologist specializing in head and neck cancer at Fred Hutchinson Cancer Center in Seattle, WA.

Children can get their first dose of HPV immunization starting at 9 years old. Doctors recommend getting two doses between the ages of 9 and 12. Teens and young adults up to age 26 who are not already immunized can still get the shots. If the vaccine series is started later, three shots may be needed instead of two.

The HPV vaccine does not treat existing HPV infections, so it is better to get immunized earlier rather than later in life. It is still worthwhile for someone to get the vaccine as a teen or adult, even if they have had an HPV infection in the past.?

Learn more about what parents, teens, and young adults should know about HPV immunization.

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Dr. Rodriguez is an Associate Editor on ASCO¡¯s Patient Information Editorial Board.