By Rebecca Bowers

EXECUTIVE SUMMARY

In a multi-year analysis of cervical precancers, data indicate that the incidence of cancers caused by human papillomavirus (HPV) types 16 and 18, which have been targeted by vaccination, has declined.

  • Researchers analyzed more than 10,000 archived specimens that were collected between 2008 and 2014 from reproductive-age women who had received a diagnosis of grade 2 or 3 cervical intraepithelial neoplasia or adenocarcinoma in situ (CIN2+). Samples were tested for 37 HPV types, with investigators looking at the proportion and estimated number of cases by HPV types over time.
  • The number of cases of CIN2+ dropped 21%, from 2,344 in 2008 to 1,857 in 2014, data indicate. Researchers report the estimated number of cases attributed to HPV types 16 and 18 declined from 1,235 in 2008 to 819 cases in 2014.

In a multi-year analysis of cervical precancers, data show declines in the incidence of cancers caused by human papillomavirus (HPV) strains 16 and 18, which have been targeted by vaccination.1 The National Cancer Institute states that most cervical cancers are caused by HPV.2

Researchers affiliated with the Centers for Disease Control and Prevention’s (CDC) Human Papillomavirus Vaccine Impact Monitoring Project analyzed more than 10,000 archived specimens. The specimens were collected between 2008 and 2014 from reproductive-age women who had received a diagnosis of grade 2 or 3 cervical intraepithelial neoplasia or adenocarcinoma in situ (CIN2+). Investigators tested the samples for 37 HPV types. They then looked at the proportion and estimated number of cases by HPV types over time.

The analysis indicates that the number of cases of CIN2+ dropped 21%, from 2,344 in 2008 to 1,857 in 2014. Researchers reported that the estimated number of cases attributed to HPV types 16 and 18 decreased from 1,235 in 2008 to 819 cases in 2014.1

Among women who were vaccinated against HPV, data reflect that the proportion of CIN2+ cases that tested positive for HPV 16/18 fell from 55.2% to 33.3%. In comparison, for unvaccinated women, the proportion of CIN2+ cases that tested positive for HPV 16/18 decreased from 51.0% to 47.3%. Among women whose vaccination status was unknown, the proportion declined from 53.7% to 45.8%. Researchers believe the decreases among unvaccinated women suggest herd protection.1

“This is clear evidence that the HPV vaccine is working to prevent cervical disease in young women in the United States,” says Nancy McClung, PhD, RN, an epidemic intelligence service officer at the CDC. “In the coming years, we should see even greater impact as more women are vaccinated during early adolescence and before exposure to HPV.”

Vaccine Makes Impact

In the current study, researchers reported that almost every age group experienced decreases in the proportion of CIN2+ cases that tested positive for HPV 16/18. However, no declines were found among women ages 35-39, the oldest age group. Researchers concluded that most of the women in this age group were not eligible to receive the HPV vaccine because of their age.

Although non-Hispanic whites and blacks experienced decreases in the proportion of precancers that were positive for HPV 16/18, Hispanic and Asian women did not. Although the women who were included in this study may have been less likely to be vaccinated against HPV, recent reports indicate robust uptake of the HPV vaccine among Hispanic and Asian teens, which should diminish racial and ethnic disparities.1

Keep Recommendations Coming

The CDC recommends that all boys and girls who are 11 or 12 years of age receive HPV vaccination. The vaccine series can be started as early as age 9. A catch-up vaccine is recommended for males through age 21 and for females through age 26. In addition, the HPV vaccine is recommended for gay and bisexual men through age 26. The vaccine also is recommended for men and women who have compromised immune systems through age 26 if they did not receive the complete vaccination at a younger age.

In October 2018, the Food and Drug Administration approved the use of the nine-valent HPV vaccine in women and men ages 27 through 45. The Advisory Committee on Immunization Practices is reviewing results from health economic analyses, as well as other data related to this policy question, with further discussion slated for its June 2019 meeting.

How can healthcare providers help to increase the HPV vaccination rates? According to the CDC, the main reason parents choose to vaccinate their children is because a healthcare provider recommended the vaccine. Clinicians can strongly recommend the vaccination against HPV to parents of children 11-12 years of age at the same time and in the same way that they recommend the meningococcal and Tdap vaccines.

More than 60 global organizations, led by the International Papillomavirus Society, have joined together to reduce the burden of HPV-related cancer. The society recently observed March 4 as International HPV Awareness Day to bring attention to the importance of vaccination and screening.

Increasing awareness of the HPV virus and the steps people can take to reduce risk is “critical,” notes Margaret Stanley, OBE FMedSci, president of the International Papillomavirus Society and emeritus professor of epithelial biology at the University of Cambridge.

“By understanding the virus and by talking openly, we can remove the misunderstandings and stigma that often act as a barrier to appropriate healthcare and put people at real risk,” said Stanley in a press statement.

Although policy and public attention have focused on HPV’s role in cervical cancer, it is important to remember that in the United States, high-risk HPV types cause 3% of all cancers in women and 2% of all cancers in men, which together result in approximately 43,000 HPV-related cancers each year.2 In the United States, most oropharyngeal cancers (70%) are caused by HPV. The number of new cases is increasing each year, and oropharyngeal cancers are now the most common HPV-related cancer in the United States.2

“The virus is carried by men as well as women, and males are also at risk of HPV-related cancers,” notes Joel Palefsky, MD, professor of medicine at the University of California, San Francisco’s Department of Infectious Diseases and advocacy chair for the International Papillomavirus Society. “Everyone is potentially affected by HPV — and everyone can do something to reduce the risks simply by sharing information and lifting the lid on HPV.”

REFERENCES

  1. McClung NM, Gargano JW, Bennett NM, et al. Trends in human papillomavirus vaccine types 16 and 18 in cervical precancers, 2008-2014. Cancer Epidemiol Biomarkers Prev 2019;28:602-609.
  2. National Cancer Institute. HPV and cancer. Fact sheet. Available at: https://bit.ly/2SJMHDc. Accessed March 21, 2019.