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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. These conditions are not yet cancer. But if they aren’t treated, there is a chance that these abnormal changes may become cervical cancer. If left untreated, it may take 10 years or more for precancerous conditions of the cervix to turn into cervical cancer, but in rare cases this can happen in less time.
Precancerous conditions of the cervix happen in an area called the transformation zone. This is where columnar cells (a type of glandular cell) are constantly being changed into 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 the human papillomavirus (HPV).
Types of precancerous conditions
Precancerous conditions of the cervix are described based on how abnormal the cells look under a microscope and how severe the cell changes are. They are grouped based on the type of cell that is abnormal. Precancerous changes in the cervix are quite common.
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). Other reporting systems refer to cervical intraepithelial neoplasia (CIN) and cervical dysplasia.
SILs are divided into low grade and high grade. CIN is graded as 1, 2 or 3.
Low-grade SIL (LSIL) compares to CIN 1. LSIL only affects cells on the surface of the cervical lining or close to it. The cervical dysplasia is mild, with changes to the cells looking only slightly different from normal cells.
High-grade SIL (HSIL) compares to CIN 2 and CIN 3. Changes to cells are deeper in the cervical lining. The cervical dysplasia is moderate to severe and the cells are considered more abnormal.
With HSIL, there are distinct changes to the size and shape of the cells so they look different from normal cells. CIN 2 is moderate to severe dysplasia. CIN 3 is severe dysplasia and also includes carcinoma in situ classification. The higher the grade the higher the risk of cancer.
Abnormal glandular cells
Atypical glandular cells (AGC) and adenocarcinoma in situ (AIS) are changes to glandular cells in the cervix. Glandular cell abnormalities are not graded and are described using the Bethesda reporting system.
AGC means the cells 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.
AIS means pre-invasive cancer cells are found. This means they haven’t spread into the deeper tissues of the cervix or surrounding tissue.
Infection with the human papillomavirus (HPV) is the main risk factor for precancerous changes in the cervix. Smoking and having a weakened immune system increase the chance that an HPV infection will not go away on its own and will develop into a precancerous condition of the cervix.
Precancerous changes in the cervix usually don’t cause any signs or symptoms. 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.
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
- an HPV test, which can sometimes be done on a sample of cervical cells taken during a Pap test
- a colposcopy exam and biopsy of any abnormal-looking areas
- an endocervical curettage, which removes cells from the endocervical canal and is usually done at the same time as a colposcopy
Most women treated for precancerous conditions of the cervix have an excellent outcome and their condition won’t develop into cervical cancer.
Mild changes to the cervix often return to normal on their own without any treatment.
More severe abnormalities are more likely to develop into cervical cancer, especially if they aren’t treated for a long time. It is hard to predict which of these will become invasive cervical cancer, so they are usually treated as soon as they are diagnosed.
Treatment options for precancerous changes in the cervix may include:
A very early stage of cancer in which abnormal cells have not yet invaded surrounding tissues.
Taking action against all cancers
The latest Canadian Cancer Statistics report found that of all newly diagnosed cancers in 2017, half are expected to be lung, colorectal, breast and prostate cancers. Learn what you can do to reduce the burden of cancer.