Prognostic factors associated with the clinical outcome of cervical intraepithelial neoplasia: a cohort study in Japan.

One hundred and eighty-five Japanese women with cervical intraepithelial neoplasia (CIN) were enrolled in this follow-up study. On the basis of the prevalence of human papillomavirus (HPV) DNA in Japanese cervical cancer patients, HPV types were categorized into three groups as follows: (1) high risk (types 16, 18, 33, 52, and 58), (2) intermediate risk (types 31, 35, 39, 51, 56, 59, 68, and 70), (3) low risk (type 6, 30, 42, 53, 54, 55, 66 and unclassified types). High-risk HPV infection was a risk factor for progression of the disease. The regression rate in the HPV negative group was higher (83.3%) than those in the HPV positive groups, but the differences in regression were no longer significant after adjustment for age and CIN grade. It is also noted that a lower cytomegalovirus IgG level and a smaller number of past pregnancies might be associated with the regression of CIN lesions.