The cervix is covered with a layer of skin-like cells on its outer surface called the ectocervix. There are also glandular cells, usually lining the inside of the cervical canal, called the endocervix. These cells produce mucus. The skin-like cells of the ectocervix can become cancerous, leading to a squamous cell cervical cancer. The glandular cells of the endocervix can also become cancerous, leading to an adenocarcinoma of the cervix. Changes to these different areas are categorised differently: cervical intraepithelial neoplasia (CIN) is the name given to cellular changes to the ectocervix and glandular cervical intraepithelial neoplasia (CGIN) represent abnormal changes to the endocervix.

Treatment for CIN depends on the degree of abnormality of the cells (see abnormal cells table). CGIN is not as common as CIN, but it is treated similarly. There is no good evidence that CGIN is more ‘aggressive’ than CIN. CGIN is harder to pick up during screening and since the cellular changes are inside the cervical canal they can be marginally more difficult to treat.

If your cervical screening result shows abnormal cells you may be asked to attend a colposcopy appointment. Remember testing positive for CIN or CGIN means that you have abnormal cervical cells that may lead to cancer if untreated, but CIN and CGIN are not in themselves cancerous. Treatment for abnormal cellular changes is usually very successful.