What are our best strategies to fight against HPV-associated cancer?
Three HPV vaccines have been approved by the US Food and Drug Administration (FDA): bivalent (2vHPV), quadrivalent (4vHPV), and 9-valent (9vHPV) vaccines. Currently, only the 9-valent HPV vaccine is available in the US. The 9-valent HPV vaccine protects against nine HPV types, including seven high-risk HPV types (HPV 16, 18, 31, 33, 45, 52, and 58) associated with cancer and two low-risk HPV types (HPV 6 and 11) associated with genital warts.
The Centers for Disease Control and Prevention (CDC) recommends HPV vaccination for girls between 9-26 years of age and boys 9-21 years of age. Ideally, individuals should be vaccinated before they are exposed to HPV infection.
The HPV vaccine is prophylactic and highly effective in preventing type-specific HPV infection, HPV infection-caused genital warts and cervical dysplasia. However, the HPV vaccine is not therapeutic; it will not prevent the progression of HPV-caused diseases among individuals who are already exposed.
The HPV vaccine is very safe. The three HPV vaccines were studied in over 74,000 individuals before being approved by the FDA. Subsequently, over 100 million doses of HPV vaccine have been distributed in the US over the past ten years with a reassuring safety profile. The most common side effects are pain, redness or swelling in the arm where the shot was given, as well as dizziness, fainting, nausea and headache.
Because the HPV vaccine is not a mandatory vaccine in the US, the current HPV uptake is around 40% in girls and 20% in boys.
Over the past 50 years, the incidence of cervical cancer has decreased by 74% in the US. This is largely due to successful cervical cancer screening programs based on Pap smear and HPV testing.
HPV testing was initially used to triage women with a cytological diagnosis of atypical squamous cells of undetermined significance (ASCUS).
For women age 30 and older, Pap smear and HPV co-testing are more sensitive at detecting cervical lesions than Pap smear alone. Co-testing also improves the detection of adenocarcinoma of the cervix.
HPV testing alone can be used as the primary cervical cancer screening method for women age 25 and older.
A recent study indicates that HPV testing-based primary cervical cancer screening significantly reduces the risk of developing cervical high grade lesions compared to Pap smear-based cervical cancer screening.