CDKN2A and infection: In order to exclude the impactions of socioenvironmental factors including marital status, family circumstances, contraception method, parities, smoking, drinking and other factors like age, menopause, lifetime sexual partners, age at first intercourse/ menarche and history of other infections, which are likely to be involved in the process of HPV persistence and cervical carcinogenesis [16-19]and therefore may influence p16/Ki-67 expression, we compared them between two groups.