Cancer occurs when cells in an area of the body grow abnormally. Cervical cancer is a cancer that begins in the cervix, the part of the uterus or womb that opens into the vagina. It is the part of the uterus that dilates and opens fully to allow a baby to pass into the birth canal. The normal cervix has two main types of cells: squamous cells that protect the outside of the cervix and glandular cells that are mostly inside the cervix which make the fluid and mucus commonly seen during ovulation. Cervical cancer is caused by abnormal changes in either of these cell types in the cervix, and is the only gynecologic cancer that can be prevented by regular screening and appropriate vaccination.

Since nearly all cervical cancers are caused by persistent infection with the Human Papillomavirus (HPV), vaccinating women and young girls before they become sexually active (currently recommended at 11 and 12 years of age) leads to the greatest prevention of pre-cancer and cancer. Early vaccination along with regular Pap tests and HPV testing when recommended is now the best way to prevent cervical cancer. Cervical cancer usually affects women between the ages of 30 and 55. More detailed information about vaccinations in the Screening and Prevention section.