The National Cancer Institute, a part of the U.S. National Institutes of Health states that persistent human papillomavirus infections are considered to be the major factor for cervical cancer. Human
papillomavirus or HPV is a group of over 100 viruses that get their name from the papillomas, better known as warts that they cause; the various viruses affect different parts of the body, for instance one type might cause warts on the appendages while others tend to affect the throat. There are also viruses that have been found to affect cells in ways that may lead to the development of cancer, such as HPV types 16, 18, which are believed to be responsible for approximately 70 percent of cervical cancers. HPV viruses such as 16 and 18, together with others that are known to increase cancer risk are called “high-risk”; the NCI notes that most high-risk HPV infections do not lead to cancer development and clear up on their own.