Human papillomavirus (HPV) is now recognized as the most important causative agent in cervical carcinogenesis at the molecular level, although HPV may not induce many of the identified molecular alterations.11,12 As many as 5% of cervical cancers may not be associated with HPV.13,14 First intercourse at an early age, sexual promiscuity, high parity, race, and low socioeconomic status are presently thought to increase the risk for cervical cancer because these factors are linked to sexual behavior that increases the likelihood of exposure to HPV and/or because they are cofactors that modify the risk in women who are infected with HPV. Tobacco smoking is also a significant independent risk factor.

http:// emedicine.medscape.com/article/402329-media