•
•
•
•
Cervical cancer is one of the most common cancers among women worldwide. Approximately 500,000 new cases are diagnosed each year, resulting in over 200,000 deaths. Cervical infection with one of about 15 oncogenic human papillomavirus (HPV) types is now known to be the cause of nearly all cervical tumors. A single HPV type, HPV-16, accounts for approximately half of all cervical cancer cases worldwide and an additional type, HPV-18 accounts for an additional 10-20% of cases. A vaccine based on the structural capsid protein of HPV has been designed to protect against infection with oncogenic HPV types 16 and 18. Pre-clinical and clinical studies to date suggest the vaccine is likely to be highly effective at preventing infection with HPV-16/18 and associated cervical lesions.
To further evaluate this promising vaccine, the NCI, in collaboration with investigators in Costa Rica, is conducting a large, phase III, population-based randomized clinical trial of the HPV-16/18 vaccine in Guanacaste, Costa Rica. Approximately 7,000 women 18-25 years of age have been enrolled into this trial and randomized into receiving the HPV-16/18 vaccine or the control vaccine Havrix (Hepatitis A). Participants are being vaccinated three times over a 6-month period. Each woman is being followed with yearly (more often if clinically indicated) clinic visits and pelvic exams for four years to obtain information on long-term safety of the vaccine and to determine whether vaccination protects against the development of HPV-16/18 infection and cervical cancer precursors associated with HPV-16/18. Biological specimens, including blood and cervical cells and secretions, are collected at each study visit to allow for careful assessment of virological, immunological and other factors. Women with evidence of serious cytological abnormalities are referred to colposcopy for evaluation and treatment.
This large trial provides a rich resource within which to evaluate vaccine efficacy, immunological mechanisms of protection, and HPV and cervical cancer natural history.
