When you're exposed to genital human papillomavirus (HPV), your immune system usually prevents the virus from doing serious harm. But sometimes, the virus survives for years. Eventually, the virus can lead to the conversion of normal cells on the surface of the cervix into cancerous cells.

At first, cells may only show signs of a viral infection. Eventually, the cells may develop precancerous changes. This is known as cervical intraepithelial neoplasia, which usually goes away spontaneously, but in some cases it may progress to invasive cervical cancer.

It's not clear why some people are more likely to develop cervical cancer. Some types of HPV are simply more aggressive than are others. Cigarette smoking, being overweight, and long-term use of oral contraceptives also increase the risk of cervical cancer.

An HPV vaccine is available. It offers protection from several of the most dangerous types of HPV.

If you're sexually active, the best way to prevent HPV and other sexually transmitted infections is to remain in a mutually monogamous relationship with an uninfected partner. Otherwise, use a condom every time you have sex. Regular cervical screening is important, too.