What vaccines prevent cancer?

Vaccines That Prevent Cancer

The HPV (human papillomavirus) vaccine is currently the only vaccine specifically designed to prevent cancer by targeting the viral causes of cervical, anal, vulvar, vaginal, penile, and oropharyngeal cancers. The hepatitis B vaccine also prevents cancer by preventing hepatitis B virus infections that can lead to liver cancer.

HPV Vaccines

Mechanism and Efficacy

• HPV vaccines work by preventing infection with specific HPV types that cause cancer
• Two HPV vaccines have been developed 1:
  • Gardasil (quadrivalent): Protects against HPV types 6,11,16, and 18
  • Cervarix (bivalent): Protects against HPV types 16 and 18
• HPV types 16 and 18 cause approximately 70% of cervical cancers 2
• HPV types 6 and 11 cause about 90% of genital warts 2
• Clinical trials showed 100% efficacy in preventing HPV16/18-related cervical intraepithelial neoplasia grade 2/3 (CIN2/3) and adenocarcinoma in situ in women who were not previously infected 1
• Real-world data shows HPV vaccination is highly effective against cervical cancer with an incidence rate ratio of 0.14 (86% reduction) for women vaccinated at age 16 or younger 3

Recommendations for HPV Vaccination

• The HPV vaccine should be offered to all individuals up to 26 years of age 1
• Optimal timing is before sexual debut, with vaccination recommended for girls aged 11-12 years 1
• Catch-up vaccination is recommended for females aged 13-26 years who have not been previously vaccinated 1
• Even after vaccination, regular cervical cancer screening is still necessary as the vaccines do not protect against all cancer-causing HPV types 2

Hepatitis B Vaccine

Cancer Prevention Mechanism

• The hepatitis B vaccine prevents infection with the hepatitis B virus (HBV)
• Chronic HBV infection is a major risk factor for hepatocellular carcinoma (liver cancer) 4
• The Taiwanese HBV vaccination program for newborns has become a model worldwide and has demonstrated significant reductions in liver cancer incidence 4

Differences in Implementation Success

Despite similarities in their cancer-preventing mechanisms, HPV and HBV vaccination programs have had different levels of success:

• HBV vaccination has achieved high coverage rates, supported by school entry mandates in most states 5
• HPV vaccination coverage has lagged behind public health goals 5
• Factors contributing to lower HPV vaccine uptake include 5:
  1. Logistical challenges of administration
  2. Parental and provider attitudes
  3. Safety concerns
  4. Cost issues

Safety Profile

• Meta-analyses show HPV vaccines have good safety profiles with most adverse reactions being transient 6
• Local injection site reactions are more common with HPV vaccines compared to placebo, but systemic symptoms are not significantly different 6
• The benefits of cancer prevention far outweigh the risks of vaccination

Future Directions

• Therapeutic HPV vaccines (to treat existing infections) are in development but have not yet shown definitive clinical efficacy for cervical neoplasia 7
• Efforts to improve HPV vaccination coverage include:
  • Gender-neutral messaging
  • School-located vaccination programs
  • Younger age of administration when possible
  • Addressing parental concerns about safety

Key Points for Clinical Practice

• HPV vaccination is most effective when administered before exposure to the virus (before sexual debut)
• Both HPV and hepatitis B vaccines are considered major successes in cancer chemoprevention 4
• Vaccination does not replace the need for appropriate cancer screening
• The HPV vaccine should be offered to all eligible patients as recommended by the NCCN guidelines 1