Prevention of HPV-related cancers through immunization.

CS21-01

Results from six randomized controlled trials of monvalent (HPV16), bivalent (HPV16/18) and quadrivalent (HPV6/11/16/18) prophylactic HPV recombinant vaccines demonstrated high-level protection from infection and lesions caused by the targeted HPV types. The vaccines were found to be generally safe and well-tolerated. The quadrivalent HPV6/11/16/18 vaccine (Gardasil®, Merck, USA), has been licensed in many countries for use among females between 9 and 26 years of age. The bivalent HPV16/18 vaccine (Cervarix™, GlaxoSmithKline, Belguim) is currently under review for licensure in Europe and soon will be submitted for review in other countries. Both vaccines, which are composed of empty viral capsids called virus-like-particles (VLP), have the potential to substantially reduce HPV-related morbidity and mortality. HPV16 and HPV18 cause about 70% of cervical cancers, 80% to 90% of anal cancers, 40% of vulvar cancers, 15% to 20% of head and neck cancers and an uncertain proportion of penile, vaginal, and urethral cancers worldwide. HPV6 and HPV11 cause at least 80% of genital warts and over 95% of a rare, but highly morbid condition called recurrent respiratory papillomatosis. Additional vaccine trial findings show that protection is durable for at least 4 to 5 years. Evidence of vaccine efficacy among young men and women older than 26 years will be available within the next couple of years. Now that prevention of many HPV-related cancers and intraepithelial lesions through vaccination has become a possibility, it is important to develop recommendations that are based on current and evolving knowledge of the optimal ages for routine and "catch-up vaccination, need for boosters, role of herd immunity, barriers to implementation, and impact on cervical cancer screening programs.