How cancer of the cervix develops

Cancer of the cervix can take many years to develop. Before it does, changes occur in the cells of the cervix. These abnormal cells are not cancerous, and are called cervical intra-epithelial neoplasia (CIN). Some doctors call these changes pre-cancerous. This means that the cells might develop into cancer in some women if they are not treated.

It is important to know that most women with CIN do not develop cancer .

CIN may also be referred to as dysplasia.

Cervical screening Back to top

Cervical screening| is a way of detecting early changes to cells in the cervix so that treatment can be given to prevent a cancer developing. Cervical screening involves taking a sample of cells from the cervix using a test known as a cervical smear. Although the aim of cervical screening is to prevent cancer, it can also sometimes detect a cancer that has already developed, before any symptoms occur.

These days, the main method of collecting the cervical cells is known as liquid-based cytology (described below). It’s used routinely as part of the UK cervical screening programme for women with no symptoms.

The smear test (using liquid-based cytology) Back to top

Liquid-based cytology (LBC) is now the most commonly used method of collecting cells from the cervix in the UK. When you have the test you’ll be asked to lie on a couch. The doctor or nurse will gently put an instrument called a speculum into your vagina to keep it open. A special brush will be used to gently take cells from the cervix. The head of the brush is then rinsed into a small container of preservative or snapped off and put into the container. The container will be sent to the laboratory for examination.

In the laboratory, the cells are put onto a glass slide. Liquid-based cytology preserves more cells, and makes the need for a repeat test less likely than with a conventional smear test (see below).

The smear test (also known as a PAP smear) Back to top

This method was used before liquid-based cytology was developed. The sample is taken in a similar way to liquid-based cytology, but the nurse or doctor will use a small disposable spatula to take the sample. Sometimes a small brush is used to collect the cells. The cells are spread onto a glass slide and sent to a laboratory to be examined under a microscope.

Our information on cervical screening| has more detailed information about these tests.

CIN and HPV Back to top

CIN is usually the result of a virus infection: the human papillomavirus (HPV)| . HPV is a very common virus that can affect the cells of the cervix. It’s mainly passed on during sex.

Most women who have had sex will have the virus at some time in their life. However, in many women their immune system will get rid of the virus and they won’t know they ever had it.

The cervical smear can detect changes in the cells of the cervix caused by HPV infection.

There are more than 100 types of HPV and each type is identified by a number (eg HPV 16). Some types of the virus can cause genital warts, and other types can cause CIN in the cells of the cervix. CIN usually clears up once the immune system has got rid of the virus. In some women the virus stays for a number of years, and in a few of these women the CIN will develop into cancer if it is not treated.

The type of HPV can affect whether CIN develops or not. Only certain types, such as 16, 18, 31 and 33 known as ‘high-risk’ types) seem to be associated with the development of CIN, and ultimately with cervical cancer.

HPV vaccine Back to top

Two vaccines to prevent HPV infection| , Gardasil® and Cervarix®, are now available in the UK. Both vaccines have been shown to protect against HPV 16 and 18 (high-risk types). It is hoped they will prevent at least 7 in 10 (70%) of the most common type of cervical cancer| (squamous cell).

These vaccines work best if they are given to children before puberty and before they start having sex. For this reason all 12–13 year-old girls in the UK are now routinely offered an HPV vaccination.

A 2-year catch up programme is also being carried out for girls up to the age of 18. These vaccines can also be obtained privately.

At present the vaccines that have been developed to prevent HPV infection are of no help in treating the condition. New research is underway to develop vaccines that are able to treat (as well as prevent) HPV infection. Although these vaccines aren’t yet available it’s hoped they will be in the future.

Our information about HPV and cancer| has more detailed information about this.

Cervical screening test results Back to top

Abnormal screening tests are usually reported as:

• mild cell changes (mild dyskaryosis)
• moderate cell changes (moderate dyskaryosis)
• severe cell changes (severe dyskaryosis).

Often if cell changes are mild, they will return to normal on their own.So you may be asked to have another screening test in a few months.

If your screening test is abnormal you’ll be referred to a hospital colposcopy unit| .

At the colposcopy unit a biopsy will be taken to confirm the diagnosis and grade of CIN.

CIN 1 refers to abnormal cells in one-third of the lining of the cervix

CIN 2 refers to abnormal cells in two-thirds of the lining of the cervix

CIN 3 refers to abnormal cells in more than two-thirds of the lining of the cervix.

Only a small number of women with CIN will develop cervical cancer, but it’s important for a doctor to check the abnormal cells.

Treatment for CIN Back to top

CIN that might develop into cancer can be treated in various ways. The aim of any treatment is to remove or destroy all of the affected cells.

This can be done using surgery, where the affected area of the cervix is removed by large loop excision| (LLETZ) or, less commonly, cone biopsy| . The affected areas can also be destroyed by laser therapy, cryotherapy or cold coagulation.

These procedures are usually carried out in an outpatient clinic by a doctor or specialist nurse, with the exception of cone biopsy, which is aminor operation that usually involves an overnight stay in hospital.

 

For detailed information about CIN and its treatment, see our information cervical screening| .