The HPV Vaccine and The Associated Risk of Developing Invasive Cervical Cancer

The HPV Vaccine and The Associated Risk of Developing Invasive Cervical Cancer
Athena Cannon, PharmD., Pharmaceutical Care Leadership Residency - Broadway Family Medicine

Background: Human papillomavirus (HPV) is one of the most common sexually transmitted infections and has been associated with genital warts, cervical lesions, oropharyngeal cancer, and anogenital cancer. The Centers for Disease Control and Prevention has estimated that annually 35,000 cases of cancer in men and women are caused by HPV infections. HPV vaccines have been shown to dramatically reduce the risk of developing HPV Infection, genital warts, and high-grade precancerous cervical lesions. Currently, evidence indicating prevention of invasive cancers later in life is limited.

Purpose: The purpose of this study is to analyze the association between girls and women who received the HPV vaccine and the risk of developing invasive cervical cancer.

Study Design: This study was a registry-based cohort study completed in Sweden using data from 2006 to 2017. The Swedish Total Population Register was used to identify females between 10 to 30 years of age who had no previous HPV vaccination or previous invasive cervical cancer. The participants were followed starting either on their tenth birthday or after January 1, 2006 and continued until either death, diagnosis of invasive cervical cancer, age 31 years old, or until December 31, 2017, whichever came first. Exposure to the quadrivalent HPV vaccine was determined using the Prescribed Drug Register and the National Vaccination Register. Girls and women were considered vaccinated if they had at least one dose of the HPV vaccination series. Those who were vaccinated were then compared to unvaccinated comparators over the same time period. Poisson regression models were used to estimate the incidence rate ratios which compared the incidence rate of those who were vaccinated with their unvaccinated counterparts.

Results: A total of 1,672,983 girls and women were included in the study. Baseline characteristics were similar in both groups. The majority of participants did not have a maternal history of cervical cancer or non-cervical cancer. Of those enrolled, 527,871 had received at least one dose of the HPV vaccine. Invasive cervical cancer was diagnosed in 19 vaccinated women and 538 unvaccinated women. After adjustment for age at follow-up, calendar year, residential and parenteral characteristics, the incidence rate ratio was 0.12 [95% confidence interval (CI), 0.00 to 0.34] in those vaccinated before 17 years of age and 0.47 [95% CI, 0.27 to 0.75] in those vaccinated between 17 to 30 years of age.

Conclusions: Administration of the quadrivalent HPV vaccine was associated with a significantly lower risk of invasive cervical cancer. The risk was lower with vaccination at a younger age. Additionally, lifestyle and health factors were not assessed in this study, such as smoking status, sexual activity, oral contraceptive use, and obesity, and other potential confounders.

Key Point: Girls and women between the ages of 10 and 30 years old receiving the HPV vaccination was associated with lower incidence of developing invasive cervical cancer.

References:

  1. Centers for Disease Control and Prevention. HPV Cancers. https://www.cdc.gov/hpv/parents/cancer.html. Accessed November 9, 2020.
  2. Lei J, Ploner A, Elfstrom M, et al. HPV vaccination and the risk of invasive cervical cancer. N Engl J Med. 2020; 383:(14)1340-48.