Cervical cancer

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Precancerous conditions of the cervix

Precancerous conditions of the cervix are changes to cervical cells that make them more likely to develop into cancer. Precancerous conditions are not yet cancer, but there is a higher chance these abnormal changes will become cervical cancer if they aren’t treated. If left untreated, it may take 10 years or more for precancerous conditions of the cervix to turn into cervical cancer, but sometimes this happens in less time.

Precancerous conditions of the cervix occur in an area called the transformation zone. This is where one type of lining (glandular, columnar cells) is constantly being changed into another type of lining (squamous cells). The transformation of columnar cells into squamous cells is a normal process, but it makes the cells more sensitive to the effect of human papillomavirus (HPV).

Precancerous changes in the cervix are quite common. They can develop at any age, but they occur most often in women in their 20s and 30s.

Infection with the human papillomavirus (HPV) is the main risk factor for precancerous changes in the cervix and cervical cancer.

Types of precancerous conditions

Precancerous conditions in the cervix are described based on how abnormal the cells look under the microscope and how severe the cell changes are. They are grouped based on the type of cell that is abnormal.

Abnormal squamous cells

Most doctors describe abnormal changes to squamous cells in the cervix using the Bethesda reporting system, which refers to squamous intraepithelial lesion (SIL). Some doctors use the terms cervical intraepithelial neoplasia (CIN) and cervical dysplasia, which are older ways of classifying changes in the cervix.

Squamous intraepithelial lesions (SILs) are divided into low grade and high grade. Low-grade SIL is called LSIL. LSIL only affects cells on or close to the surface of the cervical lining. High-grade SIL is called HSIL. It means that there are more severe changes to cells deeper in the cervical lining.

SIL, CIN and cervical dysplasia
Squamous intraepithelial lesion (SIL)Cervical intraepithelial neoplasia (CIN)Cervical dysplasiaDescription





There are early changes to the cells so they look slightly different from normal cells.

The cells are considered mildly abnormal.






There are marked changes to the size and shape of the cells so they look different from normal cells.

The cells are considered abnormal.

The changes to cells are linked with a higher risk of becoming cancer or may mean that there is an underlying cancer.

CIN III also includes carcinoma in situ (a very early stage of cancer in which tumour cells have not yet invaded surrounding tissues).

Abnormal glandular cells

Atypical glandular cells (AGC) and adenocarcinoma in situ (AIS) are changes to glandular cells in the cervix. These conditions are not graded.

Glandular cell changes
Glandular cell abnormalities (Bethesda system)Description

atypical glandular cells (AGC)

Glandular cells of the endocervix don’t look normal.

Changes to cells are linked with a higher risk of becoming cancer or may mean that there is an underlying cancer.

adenocarcinoma in situ (AIS)

Cancer cells are found in the endocervix. The cancer cells are pre-invasive, which means they haven’t spread into the deeper tissues of the cervix or surrounding tissue.

Risk factors

HPV is the most important risk factor for developing a precancerous condition of the cervix. Having more than one sex partner increases your risk of getting HPV. The following risk factors increase the chance that an HPV infection will not go away on its own and can develop into a precancerous condition of the cervix:

  • smoking
  • having a weakened immune system
  • having more than one pregnancy (called multiparity)
  • using oral contraceptives for a long time


Precancerous changes in the cervix often do not cause any signs or symptoms. But sometimes there may be spotting or bleeding after sex.

An abnormal Pap test result is often the first sign that some cells in the cervix are abnormal. This is why it is important to have regular Pap tests. Find out more about Pap test.


If a Pap test result is abnormal, you will have more tests to rule out or diagnose a precancerous condition or cervical cancer. Tests may include:

  • another Pap test after a few months (usually 6 months) if there are mild changes
  • HPV test (which can sometimes be done on a sample of cervical cells taken during a Pap test)
  • colposcopy (a procedure that uses a lighted magnifying instrument, called a colposcope, to examine the vulva, vagina and cervix) and biopsy
  • endocervical curettage (a procedure that uses a special tool, called a curette, to remove cells from the endocervical canal, usually done at the same time as a colposcopy)

Find out more about these tests and diagnosis of cervical cancer.


Most women treated for precancerous conditions of the cervix have an excellent outcome and won’t develop cervical cancer.

Mild changes to the cervix, such as LSIL, often return to normal on their own without any treatment.

More severe abnormalities (such as HSIL and AIS) are more likely to develop into cervical cancer, especially if they aren’t treated. It is hard to predict which of these will become invasive cervical cancer, so they are often treated.

Treatment options for precancerous changes in the cervix may include:


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