After decades of off-base speculation about the cause of cervical cancer, researchers now know that eight types of human papillomavirus (HPV) are responsible for 90 percent of cases of cervical cancer worldwide. The HPV family of viruses, simply put, causes warts—garden-variety warts on the hands or face, plantar warts on the soles of the feet, and even wart-like tumors of the larynx (voice box). The HPV family of viruses is quite large, with 118 types having now been cataloged. Of those, 40 like to take up residence in the genital tract, and 12 of those 40 can cause cancer.

You may have heard that polyps in the colon (lower intestine) can mutate and become cancerous. A similar kind of malignant transformation can occur among HPV in the cells of the genital tract. In women, HPV that settles in the genital tract can cause genital warts and cancer of the cervix, vulva, vagina, and anus. In men, it can cause warts or cancer of the anus and penis. It's important to understand, however, that HPV doesn't always cause warts. But just because there are no visible signs of the virus, doesn't mean it's not causing damage. See Symptoms and Diagnosis for more information.

HPV is common. According to the U.S. Centers for Disease Control and Prevention (CDC), six million people in the United States acquire HPV each year and at least 20 million already have it. Unlike chlamydia, gonorrhea, and syphilis, which are caused by contact with sexually transmitted bacteria and can be cured with antibiotics, HPV cannot be completely eradicated. Once it has evaded the immune system and settled in the genital tract, it will always remain in the body. However, exposure to HPV can be reduced, and genital warts can be treated. In addition, cervical lesions caused by HPV can be treated in a variety of ways in order to prevent the infected cells from becoming cancerous. There are also two FDA-approved vaccines to prevent the acquisition of the four strains of HPV most likely to cause cervical cancer. See Symptoms and Diagnosis for more information.