Oncogenic human papillomaviruses (HPVs) are the major cause of cervical cancer and associated cancers. First generation preventive vaccines against HPVs are entering clinical trials. Therefore, it is time to consider prerequisites of field trials in Finland.
Incidence of cervical cancer is increasing in young women which is not unexpected since risk taking behavior among young women has also increased. In the developed countries up to 44% of cervical cancer cases are attributable to HPV16 infection alone. However, high risk HPV types other than HPV16 and HPV18 are emerging in the population based on HPV DNA pilot screening studies. Annual attack rates among young women less than 25 years of age is 2.3% for HPV16 infection, and 0.03% for CIN3 invasive cervic cancer. Thus, sample size estimates for HPV vaccine efficacy trial are approximately 1000 when the endpoint is HPV16 infection, and approximately 15000 when the endpoint is >/=CIN3 or worse assuming that the vaccine efficacy is 70%. Both HPV vaccine trial acceptability and compliance rates at routine visits of the general Finnish female population are going to be high based on a pilot study.
Prerequisites for large scale field trials on HPV vaccination are fulfilled in Finland.