Vaccination of children and teenagers to prevent cervical cancer

Introduction: In disease control, prevention is superior, safer, and generally more cost-effective than treating illnesses after they develop. Vaccination, which is the administration of antigenic material to produce immunity to a disease, is one of the most important preventive measures currently at our disposal. The immune response to a vaccine may be cell-mediated or antibody-mediated, or both. Human papillomaviruses (HPVs) comprise a group of about 100 DNA nonenveloped viruses. The burden of disease related to HPV is substantial. Variable proportions of penile,1 vaginal,2 urethral,3 and head and neck cancers have been found to contain carcinogenic HPV.4-6 Cervical cancer is the most important manifestation of genital HPV infection, and is one of the leading causes of cancer mortality in women worldwide. The global disease burden of cervical cancer is estimated at 470,000 new cases, and 230,000 deaths, every year. Almost 80% of cases occur in developing countries, where it is the most common cancer among women.7 In Europe, 15,000 women die from cervical cancer each year, and it is the second most common form of cancer seen in women under 35 years of age. In Ireland, there are approximately 180 new cases annually, and about 80 deaths a year are caused by cervical cancer.8 Cervical cancer primarily affects women between 39 and 45 years of age, thereby representing an important opportunity cost in terms of potential years of life lost. The impact of the disease is accentuated further by the average age at death, often when women are still raising children. In the United States, it is estimated that over six million people are infected with genital HPV.9 Data from the National Health and Nutrition Examination Survey found a 26.8% prevalence of HPV among US girls and women, with increasing prevalence each year from ages 14 to 24 years, followed by a gradual decline in prevalence until 60.10 The risk factors for acquisition of HPV infection are shown in Table 1. Infection is extremely common in young women in their first decade of sexual activity.11 Condoms afford some protection against HPV transmission, although this protection is incomplete.5

The World Health Organisation commented recently that a vaccine to prevent oncogenic HPV infection or premalignant cervical lesions from progressing to cancer would offer a cost-effective long-term strategy to reduce the cervical cancer burden, particularly for developing countries where effective screening programmes are not available.12