Monitoring the impact of a national HPV vaccination program in Japan (MINT Study): rationale, design and methods.

We have developed a collaborative hospital-based approach to monitoring the impact of a human papillomavirus vaccine on cervical cancer, its precursor lesions and human papillomavirus type-specific prevalence in Japan. The monitoring will be conducted for a total period of 21 years on women aged <40 who are newly diagnosed with invasive cervical cancer, cervical intraepithelial neoplasia or adenocarcinoma in situ at 21 participating institutes. Women are monitored to determine their vaccine history and will be human papillomavirus-genotyped each year. The primary endpoint is the human papillomavirus16/human papillomavirus18-positive rate in women aged 16-25 who are diagnosed with invasive cervical cancer, cervical intraepithelial neoplasia grade 2/3 and adenocarcinoma in situ. The major secondary endpoints are the number of women aged <40 who are diagnosed with invasive cervical cancer, cervical intraepithelial neoplasia grade 2/3 and adenocarcinoma in situ, the human papillomavirus type-specific prevalence, and the number of deaths from invasive cervical cancer in women aged <40. Long-term surveillance for human papillomavirus-associated cervical diseases in young females is important for the development of future strategies for cervical cancer prevention in Japan.