The HPV vaccines and preventing cervical cancer

The majority of cervical cancers are caused by a very common virus called human papilloma virus (HPV). Anyone who is sexually active can contract HPV through contact with someone who already has the virus. Most women are infected with HPV at some point in their lives but may never know they have been infected. Like other viral infections such as a cold, HPV is usually cleared by the body's immune system without the need for other treatment. We do not know why a small percentage of women do not clear the infection, which can remain 'dormant' (inactive) in their bodies sometimes for many years [1] [2]. In a few women the virus may lead to the development of cervical cancer.

There are 17 high-risk strains of HPV that are responsible for 99.7% of all cervical cancers [3]. Within the high-risk group, strains 16 and 18 are the most prevalent and responsible for 70% of cervical cancers [4]. HPV infection can cause changes to the cells of the cervix creating abnormalities. Once these abnormalities become severe they can develop into cancer. That is why cervical screening is important because it can detect early changes in the cells. Vaccination for HPV can prevent infection from two of the 'highest risk' strains of HPV that cause cervical cancer.

References

Muñoz N et al. (2009) Persistence of HPV infection and risk of high-grade cervical intraepithelial neoplasia in a cohort of Colombian women. British Journal of Cancer, 100, 1184–1190.
Moscicki AB et al. (1998) The natural history of human papillomavirus infection as measured by repeat DNA testing in adolescent and young women. Journal of Pediatr, 132, 277-284.
Walboomers JMM et al. (1999) Human papillomavirus is a necessary cause of invasive cancer worldwide. Journal of Pathology, 189 (1), 12–19.
Bosch FX et al. (2008) Epidemiology and natural history of human papillomavirus infections and type-specific implications in cervical neoplasia. Vaccine, 26 (10), K1-16.

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