Cervical Cancer and Human Papillomavirus Vaccines

ABSTRACT

The necessary role of genital infection by specific types of human papillomavirus (HPV) in cervical cancer development provides an opportunity to reduce the risk of cervical cancer, a second leading cancer in women, through prophylactic vaccination. Two types of vaccines targeting HPV 16 and 18 which are responsible for about 70% of all cervical cancer worldwide have been developed a quadrivalent vaccine (Gardasil?) and a bivalent vaccine (Cervarix?). Gardasil also targets HPV 6 and 11 causing 90% of genital wart. Both two vaccines contain virus-like particles composed of L1 protein of viral capsid and do not exert infectivity. HPV vaccines were highly effective in preventing persistent infection by vaccine specific type HPV in young women who have not been previously exposed to them. Randomized double-blind placebo-controlled clinical trials have provided evidence that HPV vaccines have high efficacy against cervical precancerous lesion in young women irrespective of baseline HPV infection status. However, HPV vaccines neither treat existing HPV infections nor provide protection against all types of HPV related with cervical cancer. Therefore, even vaccinated females should take cervical cancer screening as recommended. Gardasil has been tested mainly in 9~26 years old females and Cervarix in 15~25 years old. Current recommendation for vaccination age is 9~26 years for Gardasil and 10~25 years for Cervarix, considering sexual debut and previous clinical trials. There are plenty of remaining issues regarding HPV vaccination such as vaccine efficacy in older women and in males, cost-effectiveness, duration of protection, cross-protection, potential replacement infection, and vaccine compatibility.