Human papillomavirus, or HPV, is actually a group of viruses, numbering more than 100. Some types cause warts that commonly affect hands and feet, while others cause genital warts to develop, or infections of the mouth and throat. There is a connection between HPV and cancer because some types of HPV, known as high-risk, can result in cells changing and becoming abnormal, increasing the risk that they will become cancerous. High-risk HPV infections are a form of sexually transmitted disease, and are transmitted from one person to another by direct skin contact. HPV infection can increase the risk of cervical cancer developing, as well as cancers of the mouth and throat, the penis, vagina, vulva and anus.
Although HPV and cancer are linked, many people become infected with HPV and most do not go on to develop cancer. Instead, the infection goes away on its own. Types of HPV which cause verrucas and genital warts are described as low-risk because they are not thought to be associated with abnormal cell changes in the same way as the high-risk HPVs. HPV types 16 and 18 are most frequently linked with cancer, and are thought to cause around 70 percent of all cervical cancers. While having a high-risk HPV infection increases the chance of developing cancer, the risks can also be raised by smoking or by factors which lower the body's immunity, such as illnesses like AIDS.
The main type of cancer linked with HPV, cervical cancer, can be prevented to some extent by having regular cervical screening tests, or smears. These tests detect changes in the cells of the cervix, which may be caused by an HPV infection. When abnormal cells are discovered, an investigation known as colposcopy may be carried out, where the cervix is viewed more closely. Sometimes a sample of tissue is taken to see how deeply the abnormal cells extend into the lining of the cervix. If necessary, the abnormal area can then be removed surgically using a heated wire loop.
Research into the connection between HPV and cancer has led to discoveries about how HPV causes precancerous changes in cells. While these changes cannot yet be prevented, the development of an HPV vaccine may help to stop people becoming infected in the first place. At present, a vaccine for teenage girls is available that protects against infection with HPV types 16 and 18, and it is hoped that this will lead to fewer cases of cervical cancer. Future studies into the relationship between HPV and cancer may lead to the development of vaccines which can treat those who are already infected with HPV.
