Cervical intra-epithelial neoplasia (CIN) is a term used to describe changes in the squamous cells of the cervix.
CIN is not cancer, but treatment may be needed to prevent squamous cell cervical cancer developing. You may hear some doctors use the term pre-cancerous condition to describe CIN.
Treatment isn't always needed for CIN, but if you do need treatment it's usually very successful.
Causes of CIN
Not all the causes of CIN are known. But they include:
Women who smoke are almost twice as likely to develop CIN as non-smokers.
Human papilloma virus (HPV)
The main cause of CIN is infection of the cervix with certain types of human papilloma virus (HPV). There are over 100 types of the virus, and the most common types can cause warts on the hands or verrucas on the feet. Some types can affect the genital area including the cervix, although not all of these will show any symptoms such as warts. The types of HPV that cause genital warts are not the same as the types that can lead to CIN. The types that cause genital warts are known as low-risk HPV types.
The human papilloma virus is sexually transmitted, and the possibility of contact with it increases with the number of sexual partners a woman or her partner has had. It’s more common in women who become sexually active at a young age, when their cervix may be immature and more vulnerable.
HPV is so common that most sexually active women will be exposed to it at some time in their life. There is evidence that barrier methods of contraception, such as the cap or condoms, give some protection against the spread of HPV, but they won’t cover all the susceptible areas. In most women, their body’s own immune system will get rid of the HPV naturally without them ever knowing it was there.
Some types of HPV can make women more likely to develop CIN. These are known as high-risk types of HPV. In some women they cause changes in the cervix, which show up as an abnormality during the screening tests. Very rarely, these changes can go on to develop into CIN or cervical cancer if they are left untreated. Through regular cervical screening, the changes caused by HPV can be picked up early and any treatment needed is simple and effective.