Q&A: HPV and cervical cancer
Find out the latest update on HPV and cervical cancer - what HPV is, the risk of developing a HPV infection and the role of HPV testing in screening for cervical cancer
What is HPV?
The Human Papillomavirus is an extremely common virus which affects the skin and moist membranes of the body, including the cervix, throat and anus. It is transmitted through sexual contact, including genital skin-to-skin touching.
There are high risk and low risk types. Whilst the low risk type can cause genital and skin warts, the high risk types are related to the development of cervical intraepithelial neoplasia (CIN) and cancer.
When can HPV become cancer?
The vast majority of high risk HPV infections don’t cause abnormalities and are usually cleared up by the immune system. However, factors such as immune deficiency and smoking might hinder the immune response and make the woman more susceptible to developing cervical cancer.
The strains HPV 16 and 18 are the types most likely to cause cancer, and account for over 70% of squamous cell carcinomas.
What is the lifetime risk of developing a high risk HPV infection?
The lifetime risk of developing a high risk HPV infection is a surprising 80%. Most will never know they have been infected because there are no symptoms. It is very difficult to avoid an infection with HPV because it can also transmit via skin to skin contact.
However, 70% of HPV infections clear spontaneously within 1 year, and 90% clear within 2 years. The median duration of new infections is 8 months. Whilst HPV causes 99.7% of all cervical cancers, women who develop high risk HPV lesions only have a 5-15% chance of developing cervical cancer. It will normally take up to 8-10 years after infection of HPV when you are not able to clear it to develop cervical cancer.
The vast majority of us will be able to clear the infection in the meantime and cervical cancer screening (smear) will be able to pick up women at risk.
What is the role for HPV testing in screening for cervical cancer?
99.7% of high risk HPV is attributable to developing cervical cancer. The discovery that high-risk HPV as a cause of virtually all cervical carcinoma has prompted international interest in the use of HPV DNA testing in cervical cancer screening programmes.
High-risk HPV testing will be incorporated in cervical cancer screening from 2019. Women with a positive high-risk HPV infection and abnormal smear will be referred for further investigation. HPV testing is also used for surveillance of women treated for high-grade lesions.
What will be the changes in HPV screening as a first test for cervical cancer in 2019?
The process of cervical screening is to be changed to allow women to benefit from more accurate tests. As part of the new process, the following changes are to be implemented:
- Testing for hr HPV test first
- Hr HPV positive test will have reflex cytology
- Hr HPV pos-test and abnormal cytology will be sent for colposcopy
- Women with hr HPV positive test and negative cytology: recall 12 months
- Persistent hr HPV send for colposcopy, regardless of cytology result
- Increase interval screening
Should we be vaccinating boys too?
There is a need for boys to get vaccinated as it is said that men are a ‘reservoir’ for HPV. A new Gardasil vaccine which covers more HPV strains could potentially be used to vaccinate both boys and girls between the ages of 9-26, though vaccinations at age 12/13 remain the best option to protect the individual before they become sexually active.