How does an HPV infection turn into cervical cancer?
It is well accepted that most cases of cervical cancer are caused by an HPV infection. But not all cases of HPV infection in women progress to cervical cancer. Here are some facts about the relationship between HPV and cervical cancer.
- There are many years (some researchers say between 10 and 30 years) between initial HPV infection and tumour development.
- Not all HPV strains are equal. There are many low risk strains of HPV that cause genital warts, and only a few high-risk strains that lead to cancer. HPV 16 and 18 are the most dangerous and are estimated to cause about 70% of all cervical cancers.
- New research is looking at other factors that increase the risk of HPV infection and cervical cancer development, such as the combination of bacteria found in the vagina.
- HPV prevalence in women varies depending on which country you are in (Spain has a prevalence of 1.4%, Nigeria has a prevalence of 25.6%). Prevalence of HPV subtypes also varies.
The image below illustrates how HPV infection develops into cervical cancer. It also shows the role of HPV vaccines, HPV tests, and the Pap smear in the progression timeline.